Status of network hosts
A snapshot of ARPANET host accessibility from October 12 to 22, 1971
Westheimer, E., "Status of network hosts", RFC 255, DOI 10.17487/RFC0255, October 1971, <https://www.rfc-editor.org/info/rfc255>.
@misc{rfc255,
series = {Request for Comments},
number = 255,
howpublished = {RFC 255},
publisher = {RFC Editor},
doi = {10.17487/RFC0255},
url = {https://www.rfc-editor.org/info/rfc255},
author = {E. Westheimer},
title = {{Status of network hosts}},
pagetotal = 2,
year = 1971,
month = oct,
} RFC text
Network Working Group Ellen Wentheimer
Request for Comments: 255 Bolt, Beranek and Newman
Updates: 252 October 26, 1971
NIC: 7696
This RFC reports on the status of most Network Hosts from October 12
to October 22. (Monday, October 11 was Columbus Day.) During these
two weeks, the general status of these Hosts remained as it had been
previously.
The table on the following page summarizes the daily information on
Host status for this period.
NETWORK SITE COMPUTER DAY, DATE AND TIME (Eastern)
ADDRESS T W TH F M
10/12 10/13 10/14 10/15 10/18
1530 1600 1600 1700 1730
1 UCLA SIGMA-7 O O O O O
65 UCLA IBM-360/91 O O O O O
2 SRI(NIC) PDP-10 O O #T O O
66 SRI(AI) PDP-10 D D D D D
3 UCSB IBM-360/75 O O O O O
4 UTAH PDP-10 T D T D D
69 BBN(TENEX) PDP-10 D D O O D
6 MIT(Multics) H-645 O D R T T
70 MIT(DM) PDP-10 T D T T D
8 SDC IBM-360-67 D D D D D
9 HARVARD PDP-10 O D D D D
10 LINCOLN IBM-360-67 D D D H D
NETWORK SITE COMPUTER DAY, DATE AND TIME (Eastern)
ADDRESS T W TH F
10/19 10/20 10/21 10/22
1630 1230 1330 1430
1 UCLA SIGMA-7 O O O O
65 UCLA IBM-360/91 O O O O
2 SRI(NIC) PDP-10 T O O O
66 SRI(AI) PDP-10 D D D D
3 UCSB IBM-360/75 O O D O
4 UTAH PDP-10 T D T D
69 BBN(TENEX) PDP-10 D O O O
6 MIT(Multics) H-645 T D D O
70 MIT(DM) PDP-10 D H H H
8 SDC IBM-360-67 D D D D
9 HARVARD PDP-10 D D D D
10 LINCOLN IBM-360-67 D H T H
where
D = Dead (Destination Host either dead or inaccessible [due to
network partitioning or local IMP failure] from the BBN Terminal
IMP.)
R = Refused (Destination Host returned a CLS to the initial RFC.)
T = Timed out (Destination Host did not respond in any way to the
initial RFC, although not dead.)
H = 1/2 Open (Destination Host opened a connection but then
either immediately closed it, or did not respond any further.)
O = Opened (Destination Host opened a connection and was
accessible to user.)
* The UCLA IMB-360/91 currently has Remote Job Service (NETRJS),
but has not implemented a full server Telnet System. The BBN
Terminal IMP is not equipped to test NETRJS however, we are
assuming that receipt of the UCLA explanatory message indicates
that NETRJS is also functioning.
# These sites advertise that they may not have their system
available at these times.
[This RFC was put into machine readable form for entry]
[into the online RFC archives by Kelly Tardif, Viagenie 10/99]
ISO Plain Language
On this page
§1The Reporting Period
RFC 255 reports the status of most Network Hosts from October 12 to October 22. It notes that October 11 was Columbus Day and was not included in this period.
The report's opening says the general status of the hosts remained as it had been previously. The tables provide the daily observations behind that statement.
This report covers host checks from October 12 through October 22. Its opening says the overall picture was unchanged from the earlier report.
§2How to Read the Results
The tables list a network address, site, computer, date and test result for each observation. O means the host opened a connection and was accessible to a user. D means it was dead or inaccessible from the BBN Terminal IMP; T means no response to the initial RFC, although the host was not dead.
R means the host refused the initial request. H means it opened a connection and then immediately closed it or stopped responding. A footnote explains that a marked UCLA system offered Remote Job Service but not a full Telnet server, and another mark indicates a site might be unavailable at the test time.
The letters show what happened when a host was tested. Open means it was accessible; the other codes distinguish no response, refusal, partial connection, or inaccessibility.
§3A Historical Status Snapshot
The report is a dated record, not a general guarantee that a host was always available. Each table entry reflects one test at the date and Eastern time shown.
The unit metadata records RFC 266 as the document that obsoleted RFC 255. The report itself focuses on the observations in its tables.
Each result describes one check at one listed time, not the host's availability at all times. RFC 266 later replaced this report.