Status of network hosts
ARPANET host status for October 12-22, 1971, showing stable availability.
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]
AI ELI5
On this page
§1Introduction and Testing Period
RFC 255 reports on ARPANET host status from October 12 to October 22, 1971. The text notes that Monday, October 11 was Columbus Day and was not included. During these two weeks, the general status of hosts remained as it had been in the previous report, with no significant changes in server availability or host functionality.
A report for the middle of October showed that computers stayed in the same state as before—the working ones kept working, and the broken ones stayed broken.
§2Daily Test Results
The report includes two tables of daily test results spanning October 12-22. Tests continued at random times during East Coast business hours using the same status codes: O for open, D for dead, T for timeout, H for half-open, and R for refused. Some sites marked times when they were not available for testing. UCLA's IBM-360/91 continued to offer only Remote Job Service, not a full Telnet server.
The tables showed which computers answered on each day, using the same codes as the previous reports.
§3Host Accessibility Patterns
UCLA's SIGMA-7 and IBM-360/91, and UCSB's IBM-360/75 remained consistently accessible throughout the period. SRI's NIC PDP-10 was mostly open. Several hosts remained permanently dead or unreachable, including SRI's AI PDP-10 and SDC's IBM-360. Others showed variable behavior: MIT Multics ranged from open to dead to refused; Harvard PDP-10 was mostly dead; Lincoln IBM-360 was mostly half-open; and Utah and Stanford PDP-10s were frequently dead or timed out.
The report showed which computers were reliable (UCLA and UCSB), which ones occasionally worked (MIT and Harvard), and which ones were consistently broken (Stanford and Utah).