I use NTPSYNC from Aminet. When I connect to the internet, I have this small script automatically run:
*********************************
IF "$TIMEZONE" EQ "-0400"
set flag "-d-240"
ELSE
set flag " "
ENDIF
ntpsync -c $flag time-b.nist.gov
unset flag
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It gets the current time and adjusts for my timezone and possible DST. I am also running SetDST which takes care of the Daylight Savings Time part. I don't remember for sure, but I believe SetDST creates the TIMEZONE environment variable.
Anyway, to answer your main question, time-b.nist.gov is a working time server.
Lamar