[lug] Time (again) sanity check

David L. Anselmi anselmi at anselmi.us
Wed Jun 25 21:01:54 MDT 2008


Gary Hodges wrote:
> I had to postpone my search for a WWVB or GPS time solution, but as luck 
> would have it the folks running the time server (the one with incorrect 
> time) said they would fix it.  They now claim it has the correct time, 
> but I can't seem to set my computer time correctly with it.

> hodges at machine:~$ ntpq -p
>      remote           refid      st t when poll reach   delay   offset 
>  jitter
> ============================================================================== 
> 
>  mach.nv.doe.go 151.61.251.233   2 u   26   64    5    6.862    0.174 
> 11.644

This tells you that you're synced.  In other words your time is set 
correctly.

Why are you worried about this?  Sure, I'm anal and a minute plus would 
drive me nuts for a machine on the Internet.  But usually I'd care much 
more that all the machines had the same time (for log comparisons and 
such) than that they were all just so.  Of course that should be trivial 
with ntp.

Want to hear a sea story?  Well, no, I shouldn't tell the whole thing 
here.  Suffice to say that some warships, with a myriad of GPS 
receivers, don't use the GPS signal to sync their computer clocks.  They 
do have NTP servers but only some of them are synced from shore over a 
radio link.

I was amazed.  Especially when a guy in the radio room told me he had no 
GPS signal there.  So I asked him to walk me through a time sensitive 
procedure and eventually it lead to him looking at a GPS display that 
showed not only time and location, but heading, pitch, and roll.  Wow.

Dave



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