UCI-CIP2.ARPA -185 -185250
UCI-CIP.ARPA -576 -576386
OSLO-VAX.ARPA 3738 3739395
RFC956 September 1985
Algorithms for Synchronizing Network Clocks
DEVVAX.TN.CORNELL.EDU 3657 3657026
PATCH.ARPA -86380 20411
IPTO-FAX.ARPA -86402 -1693
NETWOLF.ARPA 10651435 -62164450
Table A8. Comparison of UDP and ICMP Host Clock Offsets
Allowing for various degrees of truncation and roundoff abuse in
the various implementations, discrepancies of up to a second could
be expected between UDP and ICMP time. While the results for most
hosts confirm this, some discrepancies are far greater, which may
indicate defective implementations, excessive swapping delays and
so forth. For instance, the ICMP time indicated by UCI-CIP5.ARPA
is almost 2.5 seconds less than the UDP time.
Even though the UDP and ICMP times indicated by OSLO-VAX.ARPA and
DEVVAX.TN.CORNELL.EDU agree within nominals, the fact that they
are within a couple of minutes or so of exactly one hour early
(3600 seconds) lends weight to the conclusion they were
incorrectly set, probably by an operator who confused local summer
and standard time.
Something is clearly broken in the case of PATCH.ARPA,
IPTO-FAX.ARPA and NETWOLF.ARPA. Investigation of the PATCH.ARPA
and IPTO-FAX.ARPA reveals that these hosts were set by hand
accidently one day late (-86400 seconds), but otherwise close to
the correct time-of-day. Since the ICMP time rolls over at 2400
UT, the ICMP offset was within nominals. No explanation is
available for the obviously defective UDP and ICMP times indicated
by NETWOLF.ARPA, although it was operating within nominals at
least in the first experiment.