C

A record that lists which certificate authorities may issue certificates for a name, and under what conditions. CAs check it before issuing.

Plain language A DNS record listing which certificate authorities may issue certificates for a name.

Used in RFC 8657 RFC 9799

A device that acts as a slave station in a DOCSIS compliant cable data system, sending and receiving data over the cable network under the control of the CMTS.

Used in RFC 2670 RFC 4131 RFC 4546 RFC 4547 RFC 4639

A storage location that holds copies of data (such as web content) so that future requests for that data can be served more quickly.

Plain language A storage location holding copies of data for quick access to future requests.

Used in RFC 1914 RFC 2187 RFC 3507 RFC 3570 RFC 6392 RFC 6646 RFC 7234 RFC 7945

The value a cache uses to decide whether a stored response matches a new request. The key parameter of Cache-Status can carry a representation of it.

Plain language The value a cache uses to decide whether a stored response matches a new request.

Used in RFC 7234 RFC 9111 RFC 9211

The HTTP/1.1 header that carries caching directives such as no-cache, no-store, max-age, public and private, telling caches whether and for how long they may reuse a response.

Plain language The HTTP header carrying caching directives such as max-age and public/private.

Used in RFC 1152 RFC 1856 RFC 1862 RFC 2068 RFC 2187 RFC 2227 RFC 2295 RFC 2616 RFC 2703 RFC 3040 RFC 3229 RFC 3466 RFC 5222 RFC 5861 RFC 6202 RFC 6707 RFC 7231 RFC 7232 RFC 7234 RFC 7240 RFC 7337 RFC 7838 RFC 7933 RFC 7945 and 18 more

Calendaring Extensions to WebDAV; an HTTP-based protocol for storing, accessing, and managing calendar data on remote servers.

Plain language Calendaring Extensions to WebDAV, an HTTP-based protocol for remote calendar management.

Used in RFC 6638 RFC 7953 RFC 8607

The program that handles a user's calendar, and that receives and processes the iCalendar objects delivered by iMIP.

Plain language The program that holds a person's calendar and processes the invitations and replies that arrive.

Used in RFC 5546 RFC 6047

A controller that manages one or more media gateways, sending them commands to set up, modify, and tear down calls.

Plain language A controller managing media gateways and sending them commands for calls.

Used in RFC 2705 RFC 3435 RFC 3991 RFC 5347

A setup where the managed device opens the TCP connection to its management system instead of waiting to be contacted. The usual client and server roles above TCP stay the same.

Plain language A setup where a managed device opens the connection to its management system instead of waiting.

Used in RFC 8071 RFC 9066

A service in STIR out-of-band conveyance that stores PASSporTs so that the party receiving a call can retrieve them. It is also called a CPS.

Plain language A service storing PASSporTs so call recipients can retrieve them.

Used in RFC 8816 RFC 9888

Making a call appear to come from a telephone number the caller is not entitled to use. It is used for impersonating a person or for hiding who is really calling.

Plain language Making a call appear to come from a number the caller does not own.

Used in RFC 7340 RFC 7375 RFC 7378

A statement in a SIP INVITE request indicating what type of device or capabilities the caller wants to reach, used by proxies to filter or reorder the registered contacts for the called party.

Used in RFC 3841 RFC 4508 RFC 4596

A remote server that an OPES processor can hand work to, either to spread the workload or to use a specialized service such as virus scanning.

Plain language A remote server an OPES processor can delegate work to.

Used in RFC 3752 RFC 3836 RFC 3838 RFC 3914 RFC 4236

Camellia is the encryption algorithm that the cipher suites in RFC 5932 use. It is used in Cipher Block Chaining mode with a 128-bit or a 256-bit key and a 128-bit initialisation vector.

Plain language The block cipher these TLS cipher suites use to protect the data.

Used in RFC 5528 RFC 5932

A local candidate matched with a remote candidate. ICE sorts the pairs by priority and runs a connectivity check on each one in turn.

Plain language A local candidate matched with a remote candidate, sorted by priority for ICE connectivity checks.

Used in RFC 5245 RFC 8445 RFC 8863

One possible way to meet a policy, with its own constraints and goals. A policy can have several, and one is chosen as the active one.

Plain language One possible way to meet a policy with its own constraints, one chosen as active.

Used in RFC 9256 RFC 9862 RFC 9933 RFC 9960

The single agreed-on byte layout of a record or name ordering that signers and validators use so identical data always produces identical signatures.

Plain language The single agreed byte layout of data that signers and validators use.

Used in RFC 886 RFC 989 RFC 1630 RFC 2015 RFC 2049 RFC 2065 RFC 2469 RFC 2470 RFC 3030 RFC 3076 RFC 3156 RFC 3275 RFC 3597 RFC 3641 RFC 3862 RFC 4034 RFC 5952 RFC 7468 RFC 7638 RFC 7950 RFC 7998 RFC 8785 RFC 8949 RFC 8976 and 1 more

Turning a message into a standard form before it is hashed, so small harmless changes in transit do not change the result. DKIM defines simple and relaxed forms for the headers and body separately. The message that is actually sent is never changed.

Plain language Turning a message into a standard form before hashing so minor changes do not affect the result.

Used in RFC 1421 RFC 1848 RFC 2276 RFC 2311 RFC 2633 RFC 2802 RFC 2807 RFC 3075 RFC 3076 RFC 3156 RFC 3275 RFC 3741 RFC 3851 RFC 3930 RFC 4130 RFC 4646 RFC 4647 RFC 4826 RFC 4871 RFC 5105 RFC 5485 RFC 5646 RFC 5751 RFC 5854 and 23 more

A login or terms page that a public network shows before it grants internet access. RFC 6585 defines 511 for such networks to use.

Plain language A login or terms page shown by public networks before granting internet access.

Used in RFC 4058 RFC 6418 RFC 6585 RFC 7050 RFC 7754 RFC 8801 RFC 8908 RFC 8910 RFC 8952 RFC 9965

In Mobile IPv6, the address a mobile node uses on its current network, distinct from its home address.

Plain language In Mobile IPv6, the address a mobile node uses on its current network.

Used in RFC 2002 RFC 2290 RFC 2344 RFC 2356 RFC 2794 RFC 3024 RFC 3220 RFC 3344 RFC 3519 RFC 3583 RFC 3753 RFC 3775 RFC 3776 RFC 3963 RFC 4068 RFC 4177 RFC 4225 RFC 4260 RFC 4295 RFC 4433 RFC 4487 RFC 4636 RFC 4651 RFC 4857 and 25 more

A NAT run in the provider's network that gives customers no way to control the translation or bypass it. It is also called a CGN.

Plain language A NAT in the provider's network giving customers no way to control or bypass the translation.

Used in RFC 5720 RFC 6127 RFC 6264 RFC 6269 RFC 6333 RFC 6346 RFC 6598 RFC 6887 RFC 6888 RFC 6967 RFC 7021 RFC 7289 RFC 7393 RFC 7398 RFC 7422 RFC 7753 RFC 7857 RFC 8045 RFC 8512 RFC 9313 RFC 9386

The phone company that has authority over a block of phone numbers and controls what those numbers resolve to in ENUM.

Plain language The phone company having authority over a phone number block and controlling its ENUM resolution.

Used in RFC 5067 RFC 5526 RFC 6461

Mapping upper and lower case letters to one common form so that comparisons ignore case. Which direction is used matters for consistent results.

Plain language Mapping upper and lower case letters to a common form for case-insensitive comparison.

Used in RFC 3454 RFC 4343 RFC 4518 RFC 6885 RFC 7790 RFC 8265

Cipher Block Chaining, a way of using a block cipher in which each plaintext block is XOR'd with the previous ciphertext block before it is encrypted. The first block uses an initialization vector.

Plain language Cipher Block Chaining, where each plaintext block is XORed with the previous ciphertext before encryption.

Used in RFC 2268 RFC 2451 RFC 2574 RFC 3217 RFC 3565 RFC 3566 RFC 4196 RFC 5932 RFC 7402

A message authentication code built from a block cipher in cipher block chaining mode. Each block is XORed with the previous output and then encrypted, and the final output, possibly truncated, is the tag.

Plain language A message authentication code from a block cipher in cipher block chaining mode.

Used in RFC 3566 RFC 3610 RFC 4309 RFC 4493

Concise Binary Object Representation, a compact binary data format. EDHOC messages are made of CBOR data items.

Plain language Concise Binary Object Representation, a compact binary data format.

Used in RFC 8392 RFC 8428 RFC 8610 RFC 8618 RFC 8742 RFC 8746 RFC 8769 RFC 8949 RFC 8990 RFC 8991 RFC 9031 RFC 9052 RFC 9053 RFC 9090 RFC 9132 RFC 9148 RFC 9171 RFC 9172 RFC 9200 RFC 9237 RFC 9244 RFC 9254 RFC 9290 RFC 9338 and 15 more

A number placed in front of a CBOR data item to say what kind of thing it is, such as a date. Tags are registered with IANA.

Plain language A number placed before CBOR data indicating its type, such as a date.

Used in RFC 8392 RFC 8943 RFC 9277

A compact token format that carries claims, such as who it is for and when it expires, encoded in CBOR instead of JSON. It suits constrained devices.

Plain language A compact token format carrying claims in CBOR instead of JSON for constrained devices.

Used in RFC 8392 RFC 8747 RFC 9202

Checking Disabled. A DNS header bit set by a resolver in a query to say it will do its own validation, so the recursive server should not withhold data that failed its checks. Servers copy it into the response.

Plain language A DNS header flag indicating the resolver will do its own validation.

Used in RFC 2065 RFC 4035

The Concise Data Definition Language, a notation for describing the structure of CBOR and JSON data.

Plain language The Concise Data Definition Language, a notation describing CBOR and JSON data structure.

Used in RFC 8610 RFC 8618 RFC 8746 RFC 9165 RFC 9237 RFC 9393 RFC 9682 RFC 9741 RFC 9999 RFC 10013

Content Delivery Network Interconnection, a set of interfaces that lets separate content delivery networks cooperate. An upstream CDN can hand a request to a downstream CDN that is able to serve it.

Plain language Content Delivery Network Interconnection, interfaces letting separate CDNs cooperate.

Used in RFC 6983 RFC 7337 RFC 9241 RFC 9388

DNS records a child zone publishes to describe the DS record it wants the parent to hold. The parent can read them to update the delegation's DS records automatically.

Plain language DNS records a child zone publishes describing its desired DS record, allowing automatic parent updates.

Used in RFC 9615 RFC 9975 RFC 10026

Records a child zone publishes at its apex to tell its parent which DNSSEC key parameters it wants. The parent can use them to create or update the child's DS records.

Plain language Records a child zone publishes to tell its parent which DNSSEC key parameters it wants.

Used in RFC 7344 RFC 8078 RFC 9615

A summary of what a directory server holds: the templates and attributes it uses, plus for each attribute the list of every distinct word that appears in it. Index servers collect centroids to decide which servers to send a query to.

Plain language A summary of what a server holds, listing the words that appear in each of its fields.

Used in RFC 1835 RFC 1913

A signed document binding a public key to an identity such as a domain name. See RFC 5280.

Plain language A signed document binding a public key to an identity such as a domain name.

Used in RFC 1114 RFC 1422 RFC 1423 RFC 1424 RFC 1507 RFC 1848 RFC 1875 RFC 2094 RFC 2154 RFC 2252 RFC 2253 RFC 2311 RFC 2312 RFC 2314 RFC 2315 RFC 2487 RFC 2504 RFC 2511 RFC 2527 RFC 2538 RFC 2559 RFC 2560 RFC 2595 RFC 2631 and 222 more

An organisation that signs certificates to vouch that a public key belongs to a named server or person. Clients keep a list of CA root keys they trust.

Plain language An organization that signs certificates to vouch for a public key's association with a named entity.

Used in RFC 1421 RFC 1422 RFC 1424 RFC 1507 RFC 1704 RFC 1848 RFC 1875 RFC 1984 RFC 2094 RFC 2312 RFC 2314 RFC 2459 RFC 2510 RFC 2511 RFC 2527 RFC 2560 RFC 2585 RFC 2693 RFC 2785 RFC 2797 RFC 2818 RFC 2829 RFC 2847 RFC 2986 and 207 more

A hash of a certificate, sent in signaling so that a peer can check it against the certificate used in the TLS or DTLS handshake.

Plain language A hash of a certificate sent in signaling so peers can verify it matches the TLS handshake certificate.

Used in RFC 4572 RFC 5425 RFC 5763 RFC 7879 RFC 8122 RFC 8842 RFC 8844

CMP is a protocol for enrolling and managing the lifecycle of X.509 certificates between end entities, registration authorities and certification authorities.

Plain language A protocol for enrolling and managing the lifecycle of X.509 certificates between end entities, registration authorities, and certification authorities.

Used in RFC 9481 RFC 9483 RFC 9810

A named set of rules that governs the issuance and management of certificates within a PKI, specifying security requirements, validation procedures, and the assurance levels provided.

Plain language A named set of rules governing certificate issuance and management within a PKI.

Used in RFC 3647 RFC 5217 RFC 5914 RFC 6484 RFC 9618

The process of invalidating a digital certificate before its expiration date, typically because the certificate's private key was compromised or the certificate holder no longer controls the domain.

Used in RFC 2560 RFC 4386 RFC 6961 RFC 8240

An organization trusted to issue and sign digital certificates that bind identities to public keys.

Plain language An organization trusted to issue digital certificates binding identities to public keys.

Used in RFC 1114 RFC 2459 RFC 9810

A chain of certificates leading from a trust anchor to the certificate being checked. A path is valid only if every link passes the validation rules.

Plain language A chain of certificates from a trust anchor to the certificate being checked.

Used in RFC 2459 RFC 3379 RFC 5055 RFC 5276 RFC 5913 RFC 5914 RFC 9618

A document that specifies the practices a Certification Authority employs in issuing certificates. It is written to meet the requirements of a Certificate Policy.

Plain language A document specifying how a Certification Authority issues certificates.

Used in RFC 3647 RFC 7382

The alternating DNSKEY and DS record sets in which each link vouches for the next, running from a trust anchor down to the key that signs the data. The RFC calls it the authentication chain.

Plain language Alternating DNSKEY and DS records where each vouches for the next, running from a trust anchor.

Used in RFC 1422 RFC 2704 RFC 3090 RFC 3325 RFC 3658 RFC 3779 RFC 4033 RFC 4035 RFC 4081 RFC 4158 RFC 4230 RFC 4641 RFC 4955 RFC 5011 RFC 5074 RFC 5914 RFC 6187 RFC 6481 RFC 6487 RFC 6781 RFC 6841 RFC 6962 RFC 7344 RFC 7646 and 14 more

An authentication pattern in which one side issues a challenge and the other replies with credentials that answer it. In HTTP, the 401 response is the challenge and the retried request is the reply.

Plain language An authentication pattern where one side issues a challenge and the other replies with proof.

Used in RFC 1334 RFC 1731 RFC 1760 RFC 1789 RFC 1994 RFC 2095 RFC 2138 RFC 2195 RFC 2222 RFC 2284 RFC 2289 RFC 2433 RFC 2444 RFC 2617 RFC 2747 RFC 2759 RFC 3012 RFC 3097 RFC 3310 RFC 4186 RFC 4256 RFC 4422 RFC 4721 RFC 4959 and 14 more

A RADIUS feature, defined in RFC 5176, that lets a server change or end a user's session after it has started. It covers CoA-Request and Disconnect-Request packets sent to the access server.

Plain language A RADIUS feature letting a server change or end a user's session after it starts.

Used in RFC 5176 RFC 8045 RFC 8559

A named group of clients in IRC that all receive messages sent to the group's name. A channel is created when the first client joins it and disappears when the last one leaves.

Plain language A chat room. It exists only while at least one person is in it, and everyone in it receives each message sent to the room.

Used in RFC 1459 RFC 3117

Tying an authentication exchange to the secure channel it runs over, so the two can be shown to belong together.

Plain language Tying an authentication exchange to the secure channel it runs over.

Used in RFC 2078 RFC 2743 RFC 2744 RFC 4121 RFC 5056 RFC 5247 RFC 5387 RFC 5403 RFC 5801 RFC 5802 RFC 5836 RFC 5929 RFC 5998 RFC 6331 RFC 6677 RFC 6696 RFC 6813 RFC 6876 RFC 7055 RFC 7057 RFC 7677 RFC 7831 RFC 7861 RFC 8353 and 2 more

A frequency-diversity technique where transmissions use different frequencies at different times, following a pseudorandom pattern to evade narrow-band interference.

Plain language Jumping to different radio frequencies following a pattern to evade narrow-band interference.

Used in RFC 7554 RFC 9913

The number of bytes one side of an SSH channel may still send before it must wait for permission. The receiver raises it with a window adjust message, and it can never exceed 2^32 - 1 bytes.

Plain language The number of bytes one SSH channel side may send before waiting for permission.

Used in RFC 3081 RFC 4254

The Challenge Handshake Authentication Protocol. A PPP authentication protocol in which the authenticator sends a challenge and the peer answers with a value computed from it and a shared secret. PPP gives it the Protocol value 0xC223.

Plain language The Challenge Handshake Authentication Protocol, a PPP method where the authenticator sends changing challenges.

Used in RFC 1331 RFC 1471 RFC 1472 RFC 1548 RFC 1661 RFC 1994 RFC 2138 RFC 2284 RFC 2341 RFC 2363 RFC 2364 RFC 2433 RFC 2477 RFC 2548 RFC 2661 RFC 2759 RFC 2809 RFC 2869 RFC 2881 RFC 2989 RFC 3127 RFC 3169 RFC 3720 RFC 3723 and 10 more

A character encoding scheme is a mapping from one or several coded character sets to a sequence of octets. UTF-8 and ISO 2022 are examples.

Used in RFC 2130 RFC 6365

In MIME, a method of converting a sequence of octets into a sequence of characters, named by the charset parameter, such as US-ASCII or ISO-8859-1.

Plain language In MIME, the method of converting octets to characters, named like US-ASCII or ISO-8859-1.

Used in RFC 20 RFC 110 RFC 125 RFC 139 RFC 206 RFC 373 RFC 466 RFC 698 RFC 1345 RFC 1428 RFC 1456 RFC 1468 RFC 1489 RFC 1502 RFC 1554 RFC 1555 RFC 1556 RFC 1557 RFC 1563 RFC 1642 RFC 1815 RFC 1842 RFC 1922 RFC 1942 and 21 more

The name of the character set used to turn bytes into letters in a text body, given as a Content-Type parameter such as charset=iso-8859-1. If it is missing, US-ASCII is assumed.

Plain language The name of the character set used to decode text, given in the Content-Type parameter.

Used in RFC 1341 RFC 1521 RFC 1522 RFC 1554 RFC 1641 RFC 1767 RFC 1815 RFC 1843 RFC 1844 RFC 1874 RFC 1896 RFC 2046 RFC 2047 RFC 2130 RFC 2152 RFC 2157 RFC 2277 RFC 2278 RFC 2279 RFC 2295 RFC 2319 RFC 2376 RFC 2426 RFC 2484 and 32 more

A final digit computed from the other digits of a number so that a mistyped or mis-keyed number can be detected. In an IMEI it is the spare digit, and it is transmitted as zero even though it is stored with its computed value.

Plain language A digit at the end of a number that catches typing mistakes.

Used in RFC 6920 RFC 7254

A 2-octet field at the end of a UDP payload that a device can rewrite after changing other data. Doing so keeps the UDP checksum in the header correct without recomputing it.

Plain language A 2-byte field at the end of UDP payload that can be rewritten to keep the UDP checksum correct.

Used in RFC 7820 RFC 7821 RFC 7822

The number of bytes at the start of a datagram that the checksum protects. Coverage that is less than the full datagram length is called partial coverage.

Used in RFC 4019 RFC 5097 RFC 5597

A modification to data that preserves the Internet checksum value, allowing transport-layer protocols to detect corruption without recalculation after the modification.

Plain language A modification preserving the Internet checksum value without recalculation.

Used in RFC 6296 RFC 7915

An ESP or AH Security Association created through an IKE SA. It protects the actual data traffic, and IKE can create, rekey and delete it.

Plain language An ESP or AH Security Association created through an IKE SA for protecting actual data traffic.

Used in RFC 4555 RFC 4718 RFC 5723 RFC 5857 RFC 5996 RFC 6023 RFC 6311 RFC 7296 RFC 7619 RFC 7791 RFC 7815 RFC 8784 RFC 9347 RFC 9370 RFC 9478 RFC 9611 RFC 9867

A basic unit of SDXF data consisting of a header (chunk ID, flags, length) and content. Chunks can be elementary (holding data) or structured (containing other chunks).

Plain language A basic SDXF unit with a header (ID, flags, length) and content.

Used in RFC 2960 RFC 3072 RFC 4975 RFC 6972 RFC 7574

A way to send a message body in pieces, each preceded by its size in hexadecimal, ending with a zero-size chunk. It lets a sender start transmitting before it knows the total length.

Plain language Sending a message body in pieces, each preceded by its size in hexadecimal.

Used in RFC 2068 RFC 2616 RFC 2910 RFC 3196 RFC 4236 RFC 6202 RFC 7230 RFC 8010 RFC 9112 RFC 9292

Classless Inter-Domain Routing: the system of addressing and routing by prefixes of any length, written a.b.c.d/n, in place of fixed Class A, B and C networks.

Plain language Classless Inter-Domain Routing, addressing and routing by prefixes of any length (a.b.c.d/n).

Used in RFC 1347 RFC 1367 RFC 1375 RFC 1380 RFC 1383 RFC 1467 RFC 1481 RFC 1482 RFC 1517 RFC 1518 RFC 1519 RFC 1520 RFC 1656 RFC 1721 RFC 1722 RFC 1752 RFC 1771 RFC 1772 RFC 1773 RFC 1774 RFC 1787 RFC 1812 RFC 1817 RFC 1860 and 61 more

A mode of operation for block ciphers in which each block is combined with the previous encrypted block before it is encrypted. It starts from an initialization vector (IV).

Plain language Each block is combined with the previous encrypted block before being encrypted, starting from an initialization vector.

Used in RFC 1423 RFC 1829 RFC 1851 RFC 2040 RFC 2268 RFC 2405 RFC 2419 RFC 2420 RFC 2574 RFC 3414 RFC 3602 RFC 3943 RFC 4106 RFC 4162 RFC 4312 RFC 5932 RFC 6209 RFC 6896 RFC 7568

In TLS 1.3, a named pair of an AEAD algorithm and a hash algorithm, such as TLS_AES_128_GCM_SHA256. Key exchange and authentication are negotiated separately.

Plain language A named pair of an AEAD algorithm and a hash algorithm used in TLS, such as TLS_AES_128_GCM_SHA256.

Used in RFC 1040 RFC 1825 RFC 1827 RFC 1910 RFC 2144 RFC 2179 RFC 2246 RFC 2411 RFC 2523 RFC 2595 RFC 2612 RFC 2712 RFC 2828 RFC 2876 RFC 2910 RFC 2946 RFC 2947 RFC 2948 RFC 2949 RFC 2950 RFC 3268 RFC 3436 RFC 3607 RFC 3749 and 111 more

A block cipher mode that encrypts data without ciphertext expansion by rearranging ciphertext blocks of the final partial block, allowing the output to be the same length as the input.

Plain language A block cipher mode that encrypts data without expanding its size by rearranging the final partial block's ciphertext.

Used in RFC 2040 RFC 3962 RFC 6803 RFC 8009

A last-resort safety mechanism that stops a flow when it suffers persistent excessive congestion. It protects the network and does not replace normal congestion control.

Plain language A safety mechanism that stops a flow when it experiences persistent excessive congestion, protecting the network.

Used in RFC 8083 RFC 8084 RFC 8085

Making a packet network imitate a fixed-rate circuit, so equipment at each end behaves as if it were joined by a dedicated line.

Plain language Making a packet network behave like a fixed-rate circuit so equipment at each end acts as if connected by a dedicated line.

Used in RFC 4446 RFC 4553 RFC 4842 RFC 5086 RFC 5087 RFC 5601 RFC 6240

A number assigned by IS-IS to identify a point-to-point link. In the original IS-IS, it is an 8-bit field limiting systems to 256 point-to-point interfaces.

Used in RFC 3373 RFC 5303

A location described the way people write addresses, using elements such as country, street, building and room, rather than coordinates.

Plain language A location described like a mailing address using elements like country, street, and building, rather than coordinates.

Used in RFC 4676 RFC 4776 RFC 5139 RFC 5774 RFC 6739 RFC 6848

A name and value pair in a JWT's claims set, such as iss (issuer) or exp (expiration time). Registered names are defined by the RFC; public and private names are added by applications.

Plain language A name-value pair in a JWT's claims set, such as iss (issuer) or exp (expiration).

Used in RFC 7519 RFC 7523 RFC 7800 RFC 8055 RFC 8176 RFC 8225 RFC 8226 RFC 8292 RFC 8392 RFC 8417 RFC 8443 RFC 8485 RFC 8588 RFC 8688 RFC 8693 RFC 8725 RFC 8946 RFC 9027 RFC 9068 RFC 9101 RFC 9118 RFC 9126 RFC 9246 RFC 9470 and 12 more

An IPv4 address whose first four bits are 1110, from 224.0.0.0 to 239.255.255.255. These addresses name multicast groups rather than single hosts.

Plain language An IPv4 address from 224.0.0.0 to 239.255.255.255 that identifies a multicast group rather than a single host.

Used in RFC 988 RFC 990 RFC 1112 RFC 1117 RFC 1166 RFC 3138

One of the eight DSCPs of the form xxx000. They must map to PHBs that meet the Class Selector requirements, preserving partial compatibility with IP Precedence.

Plain language One of eight DSCPs of the form xxx000 that map to Per-Hop Behaviors meeting Class Selector requirements, preserving partial compatibility with IP Precedence.

Used in RFC 2474 RFC 2597 RFC 3086 RFC 3140 RFC 4594 RFC 5127 RFC 8622

A set of traffic flows that share the same bandwidth constraints and preemption priority rules. Up to eight Class-Types can be defined on a link, each with its own bandwidth allocation.

Plain language A set of traffic flows sharing the same bandwidth constraints and preemption priority rules; up to eight can be defined on a link.

Used in RFC 4124 RFC 4125 RFC 4126 RFC 5455

The original IPv4 plan in which the first bits of an address fixed the network size: Class A, B or C. CIDR replaced it with explicit prefix lengths.

Plain language The original IPv4 addressing scheme where the first bits determined network size, replaced by CIDR with explicit prefix lengths.

Used in RFC 791 RFC 796 RFC 917 RFC 940 RFC 943 RFC 952 RFC 990 RFC 997 RFC 1020 RFC 1044 RFC 1117 RFC 1118 RFC 1166 RFC 1338 RFC 1366 RFC 1375 RFC 1466 RFC 1467 RFC 1519 RFC 1606 RFC 1797 RFC 1878 RFC 1879 RFC 1918 and 5 more

The Customer-side Translator, a function in the device that lets IPv4-only applications work over an IPv6-only connection. It relies on a NAT64 in the network.

Plain language A function in a device that enables IPv4-only applications to work over an IPv6-only connection by relying on a NAT64 in the network.

Used in RFC 6877 RFC 7599 RFC 7849

An attack in which a malicious site loads the target site in a transparent frame over dummy buttons, so a click on the visible button actually presses a hidden one, such as an Authorize button.

Plain language An attack where a malicious site loads the target in a transparent frame over dummy buttons, so a visible click presses a hidden button.

Used in RFC 6819 RFC 7034 RFC 9700

In OAuth, an application that makes requests to protected resources on behalf of the resource owner and with its authorization. The word says nothing about where the application runs.

Plain language An application requesting permission to access a user's data.

Used in RFC 6749 RFC 6755 RFC 6819 RFC 7009 RFC 7481 RFC 7521 RFC 7522 RFC 7523 RFC 7591 RFC 7592 RFC 7636 RFC 7662 RFC 8252 RFC 8414 RFC 8628 RFC 8693 RFC 8705 RFC 8707 RFC 9101 RFC 9126 RFC 9200 RFC 9201 RFC 9203 RFC 9207 and 4 more

A small computational challenge a server hands to a client before doing expensive work. The client needs real effort to solve it, but the server can check the answer cheaply.

Plain language A small computational challenge a server gives a client before doing expensive work; the client must solve it, but the server can verify quickly.

Used in RFC 5201 RFC 7401 RFC 8019

A globally unique identifier generated by each DOTS client, typically by hashing the client certificate or pre-shared key and encoding the hash in base64url format. The CUID prevents collisions between DOTS clients, especially those from the same domain.

Used in RFC 8782 RFC 9132

In ECH, the server that holds the ECH private key and decrypts the outer ClientHello. In split mode it forwards the inner hello to a separate backend server; in shared mode it is the backend server too.

Plain language In ECH, the server holding the ECH private key that decrypts the outer ClientHello; it forwards the inner hello to a backend server in split mode.

Used in RFC 1013 RFC 9849

The first message a TLS client sends in a handshake. It lists what the client supports, and it is where extensions are offered.

Plain language The first message a TLS client sends in a handshake, listing supported capabilities and offered extensions.

Used in RFC 2818 RFC 4346 RFC 4366 RFC 6066 RFC 7250 RFC 7301 RFC 7465 RFC 7562 RFC 7685 RFC 8422 RFC 8446 RFC 8701 RFC 8744 RFC 9146 RFC 9149 RFC 9289 RFC 9846 RFC 9848 RFC 9934

The OSI Connectionless-mode Network Protocol (ISO 8473), the OSI counterpart to IP that carries packets addressed with NSAP addresses.

Plain language The OSI Connectionless-mode Network Protocol, the OSI counterpart to IP for sending packets addressed with NSAP addresses.

Used in RFC 986 RFC 994 RFC 995 RFC 1069 RFC 1238 RFC 1277 RFC 1574 RFC 1637 RFC 1888

The feedback-loop algorithm that uses NTP's final offset estimate to steer the local system clock's phase and frequency gradually, rather than jumping it.

Plain language The feedback-loop algorithm that uses NTP's offset estimate to gradually steer the local clock's phase and frequency.

Used in RFC 32 RFC 958 RFC 1059 RFC 1305 RFC 1589 RFC 5905 RFC 8039 RFC 8173 RFC 9769

How far one clock is ahead of or behind another. NTP estimates it from four timestamps as half the sum of the two one-way differences.

Plain language How far ahead or behind one clock runs compared to another; NTP estimates it from four timestamps.

Used in RFC 891 RFC 957 RFC 958 RFC 1059 RFC 1305 RFC 2330 RFC 2679 RFC 2680 RFC 2681 RFC 3393 RFC 3432 RFC 5644 RFC 5905 RFC 7244 RFC 7679 RFC 8039 RFC 8173 RFC 8575 RFC 8877 RFC 9343 RFC 9769 RFC 10030

The difference between the rate at which a clock runs and the rate of true time or of another clock. Even small skew can introduce large errors when delays are computed from two clocks.

Plain language The difference between the rate at which a clock runs and true time; even small skew can cause large errors when computing delays across two clocks.

Used in RFC 1305 RFC 2330 RFC 2730 RFC 8382

A folded spine-and-leaf network architecture where leaf nodes connect to spine nodes, which may connect to a higher level of spines (superspines or Top of Fabric). Provides high bisectional bandwidth and natural hierarchy.

Plain language A folded spine-and-leaf network architecture where leaf nodes connect to spine nodes, providing high bisectional bandwidth and natural hierarchy.

Used in RFC 7938 RFC 9696

The longest existing ancestor of a DNS name. NSEC3 responses use it to show where in the name tree a missing name would have to be.

Plain language The longest existing ancestor of a DNS name; NSEC3 uses it to show where a missing name would sit in the tree.

Used in RFC 4592 RFC 5155

A TLS message that tells the peer no more data will be sent on the connection. Receiving one lets an endpoint know a close was not caused by an attacker cutting the connection short.

Plain language A TLS message signaling that no more data will be sent on the connection, proving a close was not caused by an attacker.

Used in RFC 2246 RFC 2818 RFC 4346 RFC 6012 RFC 9289

A group of client routers managed by one or more route reflectors within a routing domain.

Plain language A group of client routers managed by one or more route reflectors within a routing domain.

Used in RFC 1966 RFC 2191 RFC 2796 RFC 6027 RFC 9342

Cipher-based Message Authentication Code. A message authentication code built on a block cipher rather than on a hash function, defined in NIST SP 800-38B.

Plain language A message authentication code that uses a block cipher instead of a hash function.

Used in RFC 5926 RFC 6803

CMC (Certificate Management over CMS) is the set of messages used to ask a certification authority to issue, revoke or renew public key certificates, and to carry the answers back. The messages travel inside Cryptographic Message Syntax (CMS) containers.

Plain language The messages for requesting a certificate from a certificate authority, and for sending the answer back.

Used in RFC 5273 RFC 6403

Common Management Information Protocol; an OSI-based network management protocol intended as an alternative to SNMP, but never widely adopted in TCP/IP networks.

Plain language Common Management Information Protocol; an OSI-based network management protocol intended as an alternative to SNMP but never widely adopted.

Used in RFC 1095 RFC 1189 RFC 1214

The Common Management Information Protocol on TCP, a way of running the ISO management protocol over the Internet protocols. It was specified in RFC 1095.

Used in RFC 1109 RFC 1189

Cable Modem Termination System, the head-end device that connects the cable radio frequency network to the Internet. It assigns and manages service flows for the cable modems it serves.

Plain language Cable Modem Termination System; the head-end device connecting the cable network to the Internet, assigning and managing service flows.

Used in RFC 2670 RFC 4131 RFC 4323 RFC 4546 RFC 4547 RFC 4639

A DNS record saying that one name is an alias for another name.

Plain language A DNS record indicating that one name is an alias for another name.

Used in RFC 882 RFC 974 RFC 1033 RFC 1279 RFC 1436 RFC 1480 RFC 1535 RFC 1536 RFC 1703 RFC 1889 RFC 1912 RFC 1985 RFC 2146 RFC 2181 RFC 2219 RFC 2308 RFC 2317 RFC 2535 RFC 2672 RFC 2782 RFC 3550 RFC 3551 RFC 3568 RFC 3861 and 42 more

The Constrained Application Protocol, a command and response protocol for microcontrollers with small RAM and ROM, designed for REST-based services.

Plain language The Constrained Application Protocol, a lightweight command-and-response protocol for microcontrollers with limited resources, designed for REST services.

Used in RFC 6574 RFC 6690 RFC 7397 RFC 7641 RFC 7925 RFC 7959 RFC 7967 RFC 8075 RFC 8132 RFC 8323 RFC 8392 RFC 8516 RFC 8613 RFC 8768 RFC 8824 RFC 8974 RFC 9019 RFC 9031 RFC 9132 RFC 9148 RFC 9176 RFC 9177 RFC 9200 RFC 9202 and 10 more

A whole number assigned to a character in a coded character set. Unicode code points are written U+ followed by four to six hexadecimal digits, such as U+00FC.

Plain language A number assigned to a character in a coded character set; Unicode code points are written as U+ followed by hex digits.

Used in RFC 2279 RFC 3260 RFC 3454 RFC 3492 RFC 3629 RFC 3692 RFC 3718 RFC 3743 RFC 3987 RFC 4020 RFC 4548 RFC 4940 RFC 5096 RFC 5129 RFC 5137 RFC 5198 RFC 5646 RFC 5704 RFC 5890 RFC 5892 RFC 5895 RFC 6365 RFC 6912 RFC 6932 and 23 more

A particular way of encoding audio or video for sending. Two endpoints must share at least one codec to exchange media.

Plain language A particular method of encoding audio or video for transmission; two endpoints must share at least one codec to exchange media.

Used in RFC 2190 RFC 2658 RFC 3264 RFC 3389 RFC 3407 RFC 3551 RFC 3625 RFC 3640 RFC 3951 RFC 3952 RFC 4123 RFC 4298 RFC 4348 RFC 4352 RFC 4424 RFC 4788 RFC 4856 RFC 5188 RFC 5334 RFC 5574 RFC 5577 RFC 6381 RFC 6501 RFC 6716 and 4 more

A coded character set is a mapping from a set of abstract characters to a set of integers. ISO 10646 and US-ASCII are examples.

Used in RFC 2130 RFC 6365

A small divisor of the group order in an elliptic curve. A group with cofactor 1 is prime-order; cofactor > 1 requires special handling in some protocols.

Plain language A small divisor of the group order in an elliptic curve; a prime-order group has cofactor 1, while cofactor > 1 requires special handling.

Used in RFC 7748 RFC 9380 RFC 9496

The process of ordering text units according to language-specific rules, as distinguished from sorting by code point values.

Plain language The process of ordering text according to language-specific rules, distinguished from sorting by code point values.

Used in RFC 3381 RFC 3536 RFC 4790 RFC 5051 RFC 5255 RFC 6067 RFC 6365

In WebDAV, a resource that contains a list of member resources, similar to a directory in a file system. A collection has properties and can be locked like any resource.

Used in RFC 2291 RFC 2518

In the syslog model, the entity that gathers syslog content for further analysis. It receives messages from originators and relays, over the transport described by the document.

Plain language The machine at the end of the line that collects log messages and stores or analyses them.

Used in RFC 6012 RFC 9326

An attack that finds two different messages with the same hash value using less work than a perfect hash algorithm would require.

Plain language An attack that finds two different messages with the same hash value using less work than a perfect hash algorithm would require.

Used in RFC 1319 RFC 2104 RFC 4270 RFC 6150 RFC 6273

Artificial background noise played or signalled during silence, so the listener does not think the line has gone dead.

Plain language Artificial background noise played during silence so the listener does not think the line has disconnected.

Used in RFC 3389 RFC 3551 RFC 4867 RFC 5574 RFC 8130

CIP is a protocol for exchanging index objects between servers, forming a mesh. Its architecture, MIME objects and transports are specified in a family of RFCs.

Used in RFC 2653 RFC 2968

A name carried in every community-based SNMP message that identifies the community the message belongs to. It acts as the access rule for the message.

Plain language A name carried in every community-based SNMP message that identifies the community and acts as the access rule.

Used in RFC 1157 RFC 1901 RFC 2287 RFC 2576 RFC 3410 RFC 3584

A named rule for comparing two strings, such as one that treats upper and lower case as the same or one that compares raw bytes.

Used in RFC 5228 RFC 5231 RFC 5255

An application-defined group of messages tied to one peer, such as a session or dialog. State and compressors are kept per compartment, and the application decides when it is created or closed.

Plain language An application-defined group of messages tied to one peer, such as a session or dialog; state and compressors are kept per compartment.

Used in RFC 3320 RFC 5049 RFC 5570

One of the disjoint subsets of resources inside a bundled link. Within a component link, a label alone is enough to identify the resource an LSP uses.

Plain language One of the disjoint subsets of resources within a bundled link; a label alone is enough to identify the resource an LSP uses.

Used in RFC 4201 RFC 7226

A document or entity consisting of multiple related components, such as a root document and embedded images or attachments.

Plain language A document consisting of multiple related components, such as a root document and embedded images or attachments.

Used in RFC 3391 RFC 6968

The NFSv4 RPC procedure that carries a sequence of operations in one request. The server runs them in order and stops at the first failure.

Used in RFC 7530 RFC 7863

Several RTCP packets sent together in one lower-layer packet. Each compound packet must begin with a Sender Report or Receiver Report.

Plain language Several RTCP packets sent together in one lower-layer packet, each beginning with a Sender Report or Receiver Report.

Used in RFC 5506 RFC 8108

Information about the current compression or decompression state of a flow, such as field values taken from earlier packets.

Plain language Information about the current compression or decompression state of a flow, such as field values from earlier packets.

Used in RFC 2508 RFC 3095 RFC 3843 RFC 4019 RFC 4362 RFC 4997 RFC 5795

A body of data known to both compressor and decompressor that acts as a pretend history in front of the data being compressed. It lets small inputs find matches that they would not contain on their own.

Plain language Data known to both compressor and decompressor that acts as a pretend history, letting small inputs find matches they would not contain alone.

Used in RFC 7400 RFC 8878 RFC 9842

The recent data a compressor and decompressor both remember so that repeated sequences can be replaced by short references. Both sides must keep their histories in step.

Plain language Recent data both a compressor and decompressor remember so repeated sequences can be replaced by short references.

Used in RFC 1967 RFC 2395 RFC 3943

A tunnel that the network sets up for a user without any action or choice by the user, in contrast to voluntary tunneling, where the user creates the tunnel.

Plain language A tunnel the network sets up for a user without any action by the user, contrasting with voluntary tunneling where the user creates it.

Used in RFC 2809 RFC 2867 RFC 2868 RFC 2881 RFC 3193

One entry in a MIB table, made up of columnar objects that share an instance identifier. Rows can be created and deleted through a status column using the RowStatus convention.

Used in RFC 1442 RFC 1903 RFC 3289 RFC 4750

A table of related values in a MIB module, made of rows that each have the same columns. Each row is identified by its index values.

Plain language A table of related values in a MIB module with rows having the same columns, each identified by its index values.

Used in RFC 1902 RFC 2578 RFC 3896 RFC 4181

A request that includes a precondition header such as If-Match, If-None-Match, If-Modified-Since or If-Unmodified-Since, so the server performs the method only if the condition holds.

Plain language A request including a precondition header such as If-Match or If-None-Match, so the server performs the method only if the condition holds.

Used in RFC 2068 RFC 2227 RFC 3229 RFC 4825 RFC 5023 RFC 5789 RFC 6585 RFC 7162 RFC 7232 RFC 7644 RFC 7808 RFC 8132 RFC 8144 RFC 8182 RFC 8246 RFC 9110 RFC 10008

A NAT that maps an internal address and port to the same external address and port for every destination. Restricted variants additionally filter which outside hosts or ports may send packets back in.

Plain language A NAT mapping an internal address and port to the same external address and port for every destination; restricted variants filter outside hosts.

Used in RFC 4380 RFC 5991

A conference template that sits at the root of a cloning tree. New conferences can be created by cloning a blueprint and inheriting its attributes.

Plain language A conference template at the root of a cloning tree from which new conferences can be created by cloning and inheriting attributes.

Used in RFC 5239 RFC 6503 RFC 6504

The specialised SIP user agent that hosts a conference, processes invitations to it and keeps a SIP dialog with each participant.

Plain language The specialized SIP user agent hosting a conference, processing invitations, and maintaining a SIP dialog with each participant.

Used in RFC 4245 RFC 4353 RFC 4575 RFC 4579 RFC 4582 RFC 4597 RFC 4722 RFC 5239 RFC 6501 RFC 7082 RFC 7701

The data that represents a conference at one stage of its life, such as a blueprint, a reservation or an active conference. It is accessed through the conference control protocol.

Plain language Data representing a conference at one stage of its life, such as a blueprint, reservation, or active conference.

Used in RFC 5239 RFC 6501 RFC 6503

A range of values given for an estimated measurement, together with a confidence level that states the probability that the true value falls inside the range. The value can still fall outside the interval.

Plain language A range around an estimate, with the chance that the true value falls inside it.

Used in RFC 5477 RFC 7459

A stretch of a path containing nodes and links that the policy of its domain says must not be disclosed outside that domain. It can be replaced by a path key when the path is passed on.

Used in RFC 5520 RFC 5553

A named store of configuration data on a server, such as running, startup or candidate, that management operations can read or edit.

Plain language A named store of configuration data on a server, such as running, startup, or candidate, that management operations can read or edit.

Used in RFC 6470 RFC 10016

The body that votes to approve or reject candidates proposed by the nominating committee. For IESG candidates, it is the IAB; for IAB candidates, it is the Internet Society Board of Trustees.

Plain language The body voting to approve or reject candidates proposed by the nominating committee; for IESG it is the IAB, for IAB it is the Internet Society Board.

Used in RFC 2282 RFC 8713

A named collection of related MIB objects or notifications that forms a unit of conformance. An agent that claims a group must implement every item in it.

Plain language A named collection of related MIB objects or notifications forming a unit of conformance; implementers must include every item.

Used in RFC 1904 RFC 2580

Random data placed in front of a message before it is encrypted, so that using a fixed starting value does not make identical messages look the same.

Plain language Random data placed in front of a message before encryption so identical messages do not look the same.

Used in RFC 2025 RFC 3961 RFC 8009

A character that looks like another, such as Cyrillic а and Latin a. Confusables can be used to fake names and mislead people.

Plain language A character that looks like another, such as Cyrillic and Latin 'a'; these can be used to fake names.

Used in RFC 4690 RFC 7564 RFC 8264

A state in which excess traffic starves other connections of access to the network. Avoiding persistent excessive congestion helps prevent it.

Plain language A state where excess traffic starves other connections of network access; avoiding persistent excessive congestion helps prevent it.

Used in RFC 896 RFC 2309 RFC 2488 RFC 2914 RFC 4336 RFC 5783 RFC 6357 RFC 8084

The rules, such as slow start, congestion avoidance and exponential backoff of the retransmission timer, that make TCP send more slowly when the network seems overloaded.

Plain language Rules such as slow start and congestion avoidance that make TCP send more slowly when the network seems overloaded.

Used in RFC 59 RFC 68 RFC 71 RFC 334 RFC 896 RFC 970 RFC 998 RFC 1016 RFC 1018 RFC 1152 RFC 1254 RFC 2001 RFC 2018 RFC 2140 RFC 2309 RFC 2331 RFC 2354 RFC 2357 RFC 2414 RFC 2415 RFC 2416 RFC 2481 RFC 2488 RFC 2525 and 309 more

The share of PCN traffic, measured in octets, that carried a mark during one measurement period. The Decision Point compares it with the CLE-limit to decide whether new flows may be admitted, and the egress node uses it to decide whether a report is needed.

Plain language A single number that shows how much of the traffic was marked as heading for trouble.

Used in RFC 6661 RFC 6662

A limit kept by the TCP sender on how much unacknowledged data it may send, set to protect the network from overload. It is often written as cwnd.

Plain language A limit the TCP sender keeps on unacknowledged data it may send, protecting the network from overload.

Used in RFC 2001 RFC 2416 RFC 2481 RFC 2488 RFC 2525 RFC 2581 RFC 2757 RFC 2861 RFC 2988 RFC 3042 RFC 3390 RFC 3465 RFC 3539 RFC 4015 RFC 5562 RFC 5681 RFC 5682 RFC 5690 RFC 5827 RFC 6582 RFC 6675 RFC 7323 RFC 7661 RFC 8087 and 9 more

A subset of routers that is connected and is adjacent to every other router. Using it as the relay set lets a flooded packet reach everyone with fewer retransmissions.

Plain language A subset of routers that is connected and adjacent to every other router; using it as the relay set reduces retransmissions.

Used in RFC 5614 RFC 6621

An identifier that each QUIC endpoint chooses for itself and that appears in packets sent to it. Because packets are matched to a connection by this value rather than by the address and port, a connection can continue after an endpoint's address changes.

Plain language An identifier each QUIC endpoint chooses for itself, appearing in packets sent to it; the connection can continue after an endpoint's address changes.

Used in RFC 65 RFC 5154 RFC 8999 RFC 9000 RFC 9146 RFC 9147 RFC 9289 RFC 9528 RFC 9853

The ability of a QUIC connection to continue after one endpoint's IP address or port changes, for example when a phone moves from Wi-Fi to cellular, by continuing to use the same connection IDs on a new path.

Plain language The ability of a QUIC connection to continue after one endpoint's IP address or port changes, by using the same connection IDs on a new path.

Used in RFC 9000 RFC 9308

The opening bytes each HTTP/2 endpoint sends. The client sends a fixed 24-octet sequence followed by a SETTINGS frame; the server sends a SETTINGS frame.

Plain language The opening bytes each HTTP/2 endpoint sends: the client sends a fixed 24-octet sequence and a SETTINGS frame, the server sends a SETTINGS frame.

Used in RFC 9113

A style of communication where each message is sent independently, with no setup step and no ongoing relationship between sender and receiver.

Plain language A communication style where each message is sent independently with no setup and no ongoing relationship between sender and receiver.

Used in RFC 161 RFC 306 RFC 342 RFC 344 RFC 353 RFC 362 RFC 366 RFC 618 RFC 671 RFC 768 RFC 787 RFC 791 RFC 873 RFC 878 RFC 948 RFC 963 RFC 969 RFC 984 RFC 994 RFC 1005 RFC 1007 RFC 1010 RFC 1086 RFC 1089 and 55 more

An attribute of a TE node that lists the valid switching combinations of that node's link termination points. For a path arriving at one termination point, the matrix names the termination points the path is allowed to leave by.

Plain language A list saying which way through a node traffic is allowed to go.

Used in RFC 7579 RFC 8795

A device with very limited memory, processing power or network capacity, so that every byte sent or stored matters.

Plain language A device with very limited memory, processing power, or network capacity so that every byte matters.

Used in RFC 6574 RFC 7397 RFC 7452 RFC 7547 RFC 7548 RFC 7744 RFC 7925 RFC 9019 RFC 9595

A small device with severe limits on power, memory and processing resources, such as a battery-powered sensor.

Plain language A small device with severe limits on power, memory, and processing resources, such as a battery-powered sensor.

Used in RFC 7228 RFC 7650 RFC 7815 RFC 8576 RFC 9453

Routing that computes paths subject to constraints such as bandwidth, hop count, delay and policy. The chosen route is not necessarily the shortest path.

Plain language Routing that computes paths subject to constraints such as bandwidth, hop count, and delay; the chosen route is not necessarily shortest.

Used in RFC 2702 RFC 3272 RFC 3785 RFC 5440

A file or stream format that wraps one or more separately encoded media streams together, adding framing and interleaving without changing the encoded data.

Plain language A file or stream format wrapping one or more separately encoded media streams together with framing and interleaving.

Used in RFC 3533 RFC 5334 RFC 7845 RFC 8794 RFC 9559

The chain of parent links that shows where a physical component sits inside a device, followed upward until a value of zero means nothing contains it.

Plain language The chain of parent links showing where a physical component sits within a device, followed upward until nothing contains it.

Used in RFC 2037 RFC 2737 RFC 4133 RFC 6933

A network of servers distributed globally to serve content to users from locations near them, reducing latency and improving performance.

Plain language A network of geographically distributed servers serving content from locations near users.

Used in RFC 3570 RFC 3914 RFC 6392 RFC 6983 RFC 7971 RFC 7975 RFC 8007 RFC 8008 RFC 8216 RFC 9538

A set of servers that deliver content to users on behalf of content providers. CDNI lets separate CDNs hand traffic to each other.

Plain language A set of servers delivering content on behalf of providers; CDNI lets separate CDNs hand traffic to each other.

Used in RFC 3897 RFC 6392 RFC 6707 RFC 6770 RFC 7336 RFC 7337 RFC 7937 RFC 8006 RFC 8586 RFC 8804 RFC 9246 RFC 9677 RFC 9808

The system through which two content networks exchange request-routing information, distribute content, and share accounting data.

Plain language The system through which two content networks exchange request-routing information, distribute content, and share accounting data.

Used in RFC 3459 RFC 3570

One line of an iCalendar object: a name, optional ;PARAM=value parameters, a colon and a value, ended by CRLF.

Plain language One line of an iCalendar object: a name, optional ;PARAM=value parameters, a colon, and a value, ended by CRLF.

Used in RFC 2445 RFC 5545

The HTTP mechanism by which a client states its preferences with Accept, Accept-Charset, Accept-Encoding and Accept-Language headers, optionally weighted with q values, and the server chooses the best matching representation of a resource.

Plain language The HTTP mechanism by which a client states preferences with Accept headers and the server chooses the best matching representation.

Used in RFC 2068 RFC 2277 RFC 2295 RFC 2296 RFC 2506 RFC 2533 RFC 2534 RFC 2616 RFC 2703 RFC 2738 RFC 2879 RFC 2912 RFC 2913 RFC 2938 RFC 2987 RFC 3066 RFC 3236 RFC 3282 RFC 3297 RFC 3840 RFC 4142 RFC 4647 RFC 5631 RFC 5646 and 18 more

An optional cache inside a CCNx forwarder that can answer requests directly. It repairs lost packets and handles bursts of requests for popular content.

Used in RFC 8569 RFC 9064 RFC 9344

One specific ICN architecture (CCN/CCNx) where content is named hierarchically and requests are forwarded based on content name rather than IP address.

Plain language One specific ICN architecture where content is named hierarchically and requests are forwarded by content name rather than IP address.

Used in RFC 7476 RFC 9139 RFC 9344 RFC 9510 RFC 9531

A random symmetric key that encrypts the content of an enveloped message. It is in turn encrypted separately for each recipient, so the bulk of the data is encrypted only once.

Plain language A random symmetric key encrypting the content of an enveloped message; it is encrypted separately for each recipient.

Used in RFC 2315 RFC 2630 RFC 2631 RFC 2876 RFC 2984 RFC 3058 RFC 3185 RFC 3211 RFC 3217 RFC 3218 RFC 3369 RFC 3370 RFC 3537 RFC 3560 RFC 3565 RFC 3851 RFC 3852 RFC 3854 RFC 4010 RFC 4909 RFC 5083 RFC 5091 RFC 5275 RFC 5402 and 27 more

A numeric identifier used in CoAP for a Media Type combined with an optional Content Coding. It keeps the label for a payload's format short.

Plain language A numeric identifier in CoAP for a Media Type combined with optional Content Coding, keeping the payload format label short.

Used in RFC 9193 RFC 9876

A unique identifier header in MIME messages that labels a specific message part or body part. Used by cid: URLs to refer to that part.

Plain language A unique identifier header in MIME messages labeling a specific message part, used by cid: URLs to refer to that part.

Used in RFC 2111 RFC 2392 RFC 6047 RFC 8262

The MIME header field that says how a body was transformed for transport. Its values are 7bit, 8bit, binary, quoted-printable and base64.

Plain language The MIME header field saying how a body was transformed for transport; values are 7bit, 8bit, binary, quoted-printable, or base64.

Used in RFC 767 RFC 1154 RFC 1341 RFC 1521 RFC 1544 RFC 1554 RFC 1740 RFC 1767 RFC 1847 RFC 2045 RFC 2048 RFC 2049 RFC 2077 RFC 2130 RFC 2157 RFC 2159 RFC 2387 RFC 2557 RFC 3156 RFC 3516 RFC 4289 RFC 5524 RFC 6532 RFC 6533

A logical association of multiple Terminations in a Media Gateway, defining the topology—how they connect and exchange media with each other—and any mixing or switching applied.

Plain language A logical association of multiple Terminations in a Media Gateway, defining their topology and how they exchange media.

Used in RFC 2885 RFC 3374 RFC 3409 RFC 3545

A number carried in compressed packets that tells the receiver which stored flow state to use when rebuilding the headers.

Plain language A number in compressed packets telling the receiver which stored flow state to use when rebuilding the headers.

Used in RFC 1975 RFC 2507 RFC 2509 RFC 3241 RFC 3544 RFC 3759 RFC 4843 RFC 4901 RFC 5795 RFC 6674 RFC 9139

A non-reserved MPLS label that a protector assigns to a context ID. It tells the protector which router's label space and IP address space to use for the packet.

Used in RFC 8372 RFC 8679

The movement of service state information from one network node to another as a means of quickly re-establishing services on a new subnet without redoing protocol exchanges from scratch.

Plain language Movement of service state from one network node to another, quickly re-establishing services without redoing protocol exchanges.

Used in RFC 3374 RFC 3726 RFC 4067

A pair of mutually reachable interfaces used for routing, signaling and link management between two nodes. It need not share the physical medium of the data links it controls.

Used in RFC 4204 RFC 4209

The long-lived TCP connection, on port 21 for FTP, over which the client sends commands and the server sends numbered replies. It follows the Telnet conventions.

Plain language The long-lived TCP connection over which an FTP client sends commands and the server sends numbered replies.

Used in RFC 2 RFC 114 RFC 354 RFC 542 RFC 959 RFC 1007 RFC 1579 RFC 2228 RFC 2389 RFC 2428 RFC 2577 RFC 2637 RFC 2661 RFC 3659 RFC 4045 RFC 4217 RFC 4454 RFC 4667 RFC 4951 RFC 5641 RFC 7121 RFC 8455

A component in a ForCES network element responsible for control-plane functions such as routing and policy management.

Plain language A component in a ForCES network element responsible for control-plane functions such as routing and policy management.

Used in RFC 3746 RFC 5810 RFC 5812 RFC 6041 RFC 6369 RFC 6956 RFC 7121 RFC 7729

A Netnews article carrying a Control header that asks an agent to take an action, such as creating a newsgroup or cancelling an article, beyond simply distributing and displaying it.

Used in RFC 5536 RFC 5537

A separate specification that extends the Media Control Channel Framework with the actual commands carried in CONTROL and REPORT messages. It must follow the template given in the framework.

Plain language A separate specification extending the Media Control Channel Framework with actual commands carried in CONTROL and REPORT messages.

Used in RFC 6230 RFC 6231 RFC 7058

The part of a network device that makes decisions about how to handle traffic, such as running routing protocols, applying policies, and managing QoS.

Plain language The part of a network device making decisions about how to handle traffic, such as running routing protocols and applying policies.

Used in RFC 3473 RFC 3654 RFC 4139 RFC 5493 RFC 5818 RFC 5882 RFC 5920 RFC 6041 RFC 6192 RFC 6398 RFC 6583 RFC 7426 RFC 8772 RFC 9673

The single unidirectional stream, identified by stream type 0x00, that each HTTP/3 endpoint opens to carry connection-wide frames such as SETTINGS, GOAWAY and MAX_PUSH_ID.

Plain language The single unidirectional stream carrying connection-wide frames such as SETTINGS, GOAWAY, and MAX_PUSH_ID in HTTP/3.

Used in RFC 466 RFC 1013 RFC 9114 RFC 9218 RFC 9412

A small header placed after the MPLS labels in a pseudowire packet. It carries protocol control bits and, optionally, a sequence number.

Plain language A small header placed after MPLS labels in a pseudowire packet, carrying protocol control bits and optionally a sequence number.

Used in RFC 547 RFC 4385 RFC 4448 RFC 4618 RFC 4619 RFC 4623 RFC 5085 RFC 5542 RFC 7079 RFC 7325 RFC 8077 RFC 8469 RFC 8964

The process by which all routers in a network reach a consistent view of the network topology and compute compatible routing paths.

Plain language The process where all routers in a network reach a consistent view of the topology and compute compatible routing paths.

Used in RFC 1246 RFC 1560 RFC 2439 RFC 3847 RFC 4061 RFC 4062 RFC 4098 RFC 6412 RFC 7980 RFC 9667

In Delay-Tolerant Networking, an adapter that lets the Bundle Protocol send and receive bundles over some native protocol such as TCP.

Plain language In Delay-Tolerant Networking, an adapter letting the Bundle Protocol send and receive bundles over native protocols such as TCP.

Used in RFC 3439 RFC 6260 RFC 7242 RFC 9174 RFC 9188

A layer in IEEE 802.16 that maps between the MAC (Media Access Control) layer and upper-layer protocols like IPv6. Different convergence sublayers handle Ethernet or IP differently.

Plain language A layer in IEEE 802.16 mapping between the MAC layer and upper-layer protocols like IPv6, handling Ethernet or IP differently.

Used in RFC 4968 RFC 5121 RFC 5154 RFC 5181

A small name/value pair, plus scope attributes, that a server asks a user agent to store and return on later matching requests. It is how HTTP, which is otherwise stateless, remembers things between requests.

Plain language A small name/value pair that a server asks a user agent to store and return on later matching requests, enabling stateless HTTP to remember things.

Used in RFC 1312 RFC 2109 RFC 2409 RFC 2696 RFC 2964 RFC 2965 RFC 3104 RFC 3568 RFC 3928 RFC 4306 RFC 4347 RFC 4454 RFC 4555 RFC 4817 RFC 4820 RFC 5062 RFC 5351 RFC 5355 RFC 5611 RFC 5971 RFC 5996 RFC 6012 RFC 6013 RFC 6113 and 30 more

The Common Open Policy Service, a query and response protocol for exchanging policy information between a policy server and its clients.

Plain language The Common Open Policy Service, a protocol for exchanging policy information between a policy server and its clients.

Used in RFC 2749 RFC 3127 RFC 3181 RFC 3317 RFC 3318 RFC 3521 RFC 4097 RFC 4261

In CBT, the designated router that acts as the central meeting point for all senders and receivers of a multicast group, similar to a rendezvous point (RP) in other protocols.

Plain language In CBT, the designated router acting as the central meeting point for all senders and receivers of a multicast group.

Used in RFC 2189 RFC 2201

A node that communicates with a mobile node. It may reach the mobile node through its home agent, or, when route optimisation is in use, directly.

Plain language Another host that talks to the mobile device, such as a server or a chat partner.

Used in RFC 4283 RFC 5380 RFC 6089

CBOR Object Signing and Encryption is a standard way to sign and encrypt CBOR data. CoSWID uses it to protect tags.

Plain language CBOR Object Signing and Encryption; a standard way to sign and encrypt CBOR data, used by CoSWID to protect tags.

Used in RFC 8392 RFC 8613 RFC 8812 RFC 9053 RFC 9360 RFC 9393 RFC 9528 RFC 9711 RFC 9921 RFC 9942 RFC 9964

A signature made over another signature value rather than over the original content. In CMS it is an unsigned attribute of a SignerInfo.

Plain language A signature made over another signature value rather than over the original content.

Used in RFC 2315 RFC 2630 RFC 2634 RFC 2649 RFC 2985 RFC 3369 RFC 3852 RFC 5126 RFC 5652 RFC 5752 RFC 5754 RFC 6211 RFC 8702 RFC 9338 RFC 9393 RFC 9688 RFC 9921

A failure mode of distance-vector routing in which routers keep raising the metric of a vanished network by passing it back and forth until it reaches infinity, which is 16 in RIP.

Plain language A failure mode of distance-vector routing where routers keep raising a vanished network's metric until it reaches infinity (16 in RIP).

Used in RFC 1009 RFC 1058 RFC 1075 RFC 1164 RFC 2080 RFC 2453 RFC 8966

The Common Profile for Instant Messaging, or CPIM, is a specification that defines the operations needed for interworking between diverse instant messaging protocols. RFC 3862 defines the message format that CPIM-compliant protocols use.

Plain language The common profile that lets different instant messaging protocols talk to each other.

Used in RFC 3862 RFC 3922

Constraint-based routed LDP, defined in RFC 3212. It extends the Label Distribution Protocol so that paths can be set up using extra information such as quality-of-service parameters.

Plain language Constraint-based routed LDP, extending the Label Distribution Protocol so paths can be set up using quality-of-service parameters.

Used in RFC 3210 RFC 3213 RFC 3214 RFC 3215 RFC 3468 RFC 3472 RFC 3475

A way to recover from a failed path setup by returning to an earlier node and trying another route, instead of giving up at the source straight away.

Plain language A way to recover from failed path setup by returning to an earlier node and trying another route, instead of giving up at the source.

Used in RFC 4139 RFC 4920 RFC 5151 RFC 5152 RFC 7926

A 32-bit cyclic redundancy check used by SCTP to detect damaged packets. It is computed over the common header and the chunks of each packet.

Plain language A 32-bit cyclic redundancy check used by SCTP to detect damaged packets, computed over the common header and chunks.

Used in RFC 1044 RFC 7143 RFC 9260 RFC 9653 RFC 9868

A server that authenticates a roaming user and then uploads or downloads that user's secured credentials, keeping them in one or more credential stores.

Used in RFC 3157 RFC 3760

A count of octets that a sender is currently allowed to send toward a queue. The sender subtracts what it sends and stops at zero until the receiver grants more.

Plain language A count of octets a sender is allowed to send toward a queue; the sender subtracts what it sends and stops at zero until receiving more.

Used in RFC 9893 RFC 9894 RFC 9895

A real-time process that checks whether an account has credit, reserves it, deducts what is used and refunds any reserved credit that was not used.

Plain language A real-time process checking whether an account has credit, reserving it, deducting what is used, and refunding unused credit.

Used in RFC 3702 RFC 8506

An attack in which an observer who sees the length of compressed, encrypted data can learn about the plain data, for example authentication credentials. It is the reason this RFC forbids authentication after compression starts.

Plain language An attack where an observer seeing compressed encrypted data length can learn about plaintext, such as authentication credentials.

Used in RFC 7541 RFC 8054

A certificate or CRL extension marked so that software which does not understand it must reject the certificate rather than ignore the extension.

Plain language A certificate or CRL extension marked so software not understanding it must reject the certificate rather than ignore it.

Used in RFC 3280 RFC 7179

Certificate revocation list. A signed list from a CA of certificates that should no longer be trusted before they expire.

Plain language Certificate revocation list; a signed list from a CA of certificates that should no longer be trusted before they expire.

Used in RFC 1421 RFC 1422 RFC 1423 RFC 1424 RFC 2094 RFC 2312 RFC 2315 RFC 2459 RFC 2510 RFC 2538 RFC 2559 RFC 2560 RFC 2585 RFC 2587 RFC 2630 RFC 2632 RFC 2692 RFC 3125 RFC 3126 RFC 3161 RFC 3279 RFC 3280 RFC 3379 RFC 3647 and 81 more

The two-character line ending made of carriage return (%x0D) followed by line feed (%x0A). RFC 5234 calls it the Internet standard newline.

Plain language The two-character line ending made of carriage return (%x0D) followed by line feed (%x0A), the Internet standard newline.

Used in RFC 571 RFC 821 RFC 934 RFC 937 RFC 959 RFC 1288 RFC 1413 RFC 1459 RFC 1848 RFC 1870 RFC 1945 RFC 2046 RFC 2060 RFC 2088 RFC 2244 RFC 2812 RFC 2813 RFC 2854 RFC 3501 RFC 3676 RFC 3977 RFC 4037 RFC 4180 RFC 4234 and 6 more

A certificate in which one certification authority vouches for the public key of another authority that is neither its parent nor its child in the naming hierarchy.

Plain language A certificate where one certification authority vouches for the public key of another authority that is neither its parent nor child.

Used in RFC 1507 RFC 4210 RFC 5217

A table entry that links two endpoints of a circuit so that traffic arriving on one is forwarded out of the other. In this MIB a cross-connect row joins a Frame Relay endpoint and an ATM endpoint.

Plain language A table entry linking two circuit endpoints so traffic arriving on one is forwarded out of the other.

Used in RFC 2955 RFC 5818 RFC 6383

A browser mechanism that lets a server approve exceptions to the same-origin policy. For some requests the browser first sends a preflight request to check for approval.

Plain language Cross-Origin Resource Sharing; a browser mechanism letting a server approve exceptions to the same-origin policy.

Used in RFC 6202 RFC 6454 RFC 7033 RFC 7480 RFC 8826 RFC 10017

An attack where a malicious site makes the victim's browser send a request that carries the victim's cookies. Defenses include SameSite cookies, a CORS check with a custom header, and anti-forgery tokens.

Plain language Cross-Site Request Forgery; an attack where a malicious site makes the victim's browser send an unauthorized request.

Used in RFC 6819 RFC 10017

A check that ties the key material of an outer tunnel to the inner authentication run inside it. It shows that the same two parties took part in both, which defeats a man in the middle.

Plain language A check tying the key material of an outer tunnel to the inner authentication run inside it, defeating man-in-the-middle attacks.

Used in RFC 7170 RFC 9930

The ability of a protocol to switch to a different cryptographic algorithm without being redesigned. This is usually done by carrying an identifier that says which algorithm is in use.

Plain language The ability of a protocol to switch to a different cryptographic algorithm without being redesigned.

Used in RFC 7343 RFC 8576

Mixing the keys of an outer tunnel and an inner authentication method into new keys, so that both are proven to end at the same endpoints. It counters tunnel man-in-the-middle attacks.

Plain language Mixing the keys of an outer tunnel and inner authentication into new keys so both are proven to end at the same endpoints.

Used in RFC 5281 RFC 6678 RFC 6813 RFC 7029

A mathematical function that turns a file or message of any size into a fixed-length fingerprint. Two different files will almost certainly produce different hashes, so if a file changes even slightly, its hash changes completely.

Plain language A mathematical function turning a file or message of any size into a fixed-length fingerprint that changes completely if anything modifies it.

Used in RFC 1805 RFC 1810 RFC 3174 RFC 3874 RFC 4418 RFC 9904

A function that maps input of any length onto a fixed-length output. It is meant to be hard to recover the input or to find two different inputs with the same output.

Plain language A function mapping input of any length onto fixed-length output, meant to be hard to reverse or to find collisions.

Used in RFC 2104 RFC 3174 RFC 4822 RFC 5831 RFC 6234 RFC 7091 RFC 7693 RFC 9106 RFC 9905

CMS is a format for signing, authenticating and encrypting data. Content is wrapped in nested layers, each identified by an object identifier.

Plain language A format for signing, authenticating, and encrypting data using nested layers, each identified by an object identifier.

Used in RFC 2633 RFC 2634 RFC 2660 RFC 3125 RFC 3274 RFC 3851 RFC 3859 RFC 4108 RFC 4134 RFC 4998 RFC 5084 RFC 5126 RFC 5272 RFC 5402 RFC 5409 RFC 5751 RFC 5911 RFC 5914 RFC 5934 RFC 5959 RFC 6010 RFC 6031 RFC 6033 RFC 6318 and 10 more

A standard format for encrypting and signing data, used as the foundation for S/MIME and other secure protocols.

Plain language A standard format for encrypting and signing data, used as the foundation for S/MIME and other secure protocols.

Used in RFC 2630 RFC 2797 RFC 3211 RFC 3851 RFC 4010 RFC 4108 RFC 4134 RFC 4490 RFC 4556 RFC 5485 RFC 5751 RFC 5754 RFC 5958 RFC 5959 RFC 6019 RFC 6031 RFC 6032 RFC 6210 RFC 6211 RFC 6476 RFC 6492 RFC 8358 RFC 8419 RFC 8551 and 11 more

The logical view that PKCS #11 gives applications of a device holding cryptographic objects such as keys and certificates. A token sits in a slot.

Plain language The logical view that PKCS #11 gives applications of a device holding cryptographic objects like keys and certificates.

Used in RFC 4758 RFC 7512

An IPv6 address formed by hashing together the subnet prefix, a random nonce and a public key. Signing with the matching private key shows the sender may claim the address.

Plain language An IPv6 address formed by hashing the subnet prefix, a nonce, and a public key.

Used in RFC 3971 RFC 5269 RFC 5533 RFC 7421 RFC 7430

An IPv6 address derived from a public key so that its owner can prove ownership by signing messages with the matching private key. SEND uses these addresses.

Plain language An IPv6 address derived from a public key so the owner can prove ownership by signing messages with the matching private key.

Used in RFC 3972 RFC 4982 RFC 5533 RFC 5535 RFC 5909 RFC 6496 RFC 7219

The science of encoding information in a form that only authorized parties can read, typically using mathematical algorithms and keys.

Plain language The science of encoding information so only authorized parties can read it, typically using mathematical algorithms and keys.

Used in RFC 1826 RFC 8423

A Computer Security Incident Response Team, a group that handles reports of computer security incidents and helps resolve them for its constituency.

Plain language A Computer Security Incident Response Team; a group handling computer security incident reports and resolving them for its constituency.

Used in RFC 2350 RFC 3013 RFC 3067 RFC 5070 RFC 6046 RFC 6545 RFC 7970 RFC 8134

A packet that lists all the LSPs a router currently holds, used to synchronize the link state database with neighbors.

Plain language Complete Sequence Number PDU; a packet listing all LSPs a router holds, used to synchronize the link state database with neighbors.

Used in RFC 2973 RFC 3847 RFC 5303

A cryptographically secure pseudorandom number generator: a source of random-looking numbers that attackers cannot predict. Good UUIDs of the random kinds should draw from one.

Plain language A cryptographically secure pseudorandom number generator; a source of random-looking numbers attackers cannot predict.

Used in RFC 8682 RFC 8937 RFC 9562 RFC 9853 RFC 9980 RFC 9986

A message containing a public key and the names it should be certified for, signed with the matching private key and sent to a certificate authority.

Plain language Certificate Signing Request; a message containing a public key and names it should be certified for, sent to a certificate authority.

Used in RFC 2986 RFC 4211 RFC 5272 RFC 5274 RFC 6492 RFC 6955 RFC 7030 RFC 7633 RFC 7894 RFC 7958 RFC 8295 RFC 8555 RFC 8635 RFC 8739 RFC 9115 RFC 9148 RFC 9444 RFC 9448 RFC 9538 RFC 9640 RFC 9642 RFC 9646 RFC 9733 RFC 9763 and 6 more

Contributing source. In RTP, an SSRC of a source that contributed to a stream combined by a mixer; the mixer lists them after the fixed header.

Plain language Contributing source; in RTP, an SSRC of a source contributing to a stream combined by a mixer.

Used in RFC 1889 RFC 2508 RFC 2862 RFC 3550 RFC 6465 RFC 7656 RFC 7667 RFC 8108 RFC 9071 RFC 9335

In TFMCC, the receiver that reports the lowest TCP-friendly rate. The sender sets its sending rate to follow this receiver.

Used in RFC 4654 RFC 5740

A way of splitting a long result list into pages, where the server hands the client an opaque marker that says where the next page begins. The client sends it back to continue.

Plain language A way of splitting a long result list into pages, where the server provides an opaque marker indicating where the next page begins.

Used in RFC 8977 RFC 9865

Moving responsibility for reliable delivery of a bundle from one DTN node to another. The node that accepts it is called a custodian and acknowledges with a custody signal.

Plain language Moving responsibility for reliable bundle delivery from one DTN node to another; the accepting node is called a custodian.

Used in RFC 4838 RFC 5050

An AS together with all the ASes that can be reached from it following only provider-to-customer links. It is used to estimate how many prefixes an ISP must list in its RPF lists.

Used in RFC 7908 RFC 8704

The customer's own device that connects a customer site to the provider's network, usually through a Provider Edge device.

Plain language The customer's device connecting a customer site to the provider's network, usually through a Provider Edge device.

Used in RFC 3985 RFC 4026 RFC 4031 RFC 4111 RFC 4553 RFC 4665 RFC 5251 RFC 5824 RFC 5921 RFC 6074 RFC 6624 RFC 7209 RFC 7338 RFC 7387 RFC 8466 RFC 9182

The router at a customer's home or small office that connects the local network to the Internet service provider.

Plain language The router at a customer's home or small office connecting the local network to an Internet service provider.

Used in RFC 6204 RFC 6513 RFC 9096 RFC 9818

The equipment at the customer edge, such as a home router, that terminates the customer end of an IPv6 transitional tunnel.

Plain language Equipment at the customer edge, such as a home router, that terminates the customer end of an IPv6 transitional tunnel.

Used in RFC 4029 RFC 5713 RFC 5851 RFC 8026

A small check value computed from data with a polynomial. The receiver recomputes it to detect whether the data was damaged.

Plain language A small check value computed from data with a polynomial; the receiver recomputes it to detect whether the data was damaged.

Used in RFC 935 RFC 1952 RFC 2761 RFC 3095 RFC 3720 RFC 4326 RFC 4362 RFC 4815 RFC 5044 RFC 5795 RFC 6846 RFC 9639

A script (writing system) used to write many Slavic and other Eastern European languages, including Russian, Bulgarian, Ukrainian, and Serbian.

Plain language A script used to write many Slavic and Eastern European languages, including Russian, Bulgarian, Ukrainian, and Serbian.

Used in RFC 2319 RFC 5992