NIST NTP servers

Tue May 10 15:36:47 UTC 2016

On 5/10/2016 11:22 AM, Leo Bicknell wrote:
> In a message written on Mon, May 09, 2016 at 11:01:23PM -0400, b f wrote:
>> In search of stable, disparate stratum 1 NTP sources.
> 
> http://wpollock.com/AUnix2/NTPstratum1PublicServers.htm
> 
>> We tried using “time.nist.gov” which returns varying round-robin addresses
>> (as the link says), but Cisco IOS resolved the FQDN and embedded the
>> numeric address in the “ntp server” config statement.
> 
> Depending on your hardware platform your Cisco Router is likely not
> a great NTP server.  IOS is not designed for hyper-accuracy.
> 
>> After letting the new server config go through a few days of update cycles,
>> the drift, offset and reachability stats are not anywhere as good as what
>> the stats for the Navy time server are - 192.5.41.41 / tock.usno.navy.mil.
> 
> The correct answer here is to run multiple NTP servers in your
> network.  ...
>[snip]

I think the correct answer here starts with a question --- what level of
time accuracy is required for the local NTP server(s)? Which then begs
the question, what level of accuracy is needed for the clients?

A shop with a client need for nanosecond accuracy begs for an entirely
different solution set than a shop where a millisecond of accuracy is
needed on the clients, and still a different solution set that a shop
where "a few milliseconds either way" is quite OK.