NTP question

Brandon Martin lists.nanog at monmotha.net
Wed May 1 22:44:18 UTC 2019

On 5/1/19 5:35 PM, Harlan Stenn wrote:
> - Why do folks want to have one or more NTP server masters that have at
> least 1 refclock on them in a data center, instead of having their data
> center NTP server masters that only get time over the internet?

It can be extremely useful to have known-good timestamps to within 
several milliseconds, even in the event of a connectivity outage, when 
trying to figure out what went wrong from log entries spanning multiple 
systems and sites.

Think about what might happen if you lost time sync as a result of the 
incident causing said connectivity outage.  Depending on your time 
sources available, you might see rapid drift or, worst case, lose your 
time reference entirely as a result of equipment restarts, etc.  GPS, as 
long as you have a good view of the sky, provides extremely accurate 
"lights out" time info, both absolute and relative, from a single source 
with no (mostly) strings attached for that purpose.
Brandon Martin

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