[ntp:questions] "good enough" ntp configuration

David J Taylor david-taylor at blueyonder.not-this-bit.nor-this-part.co.uk
Sat Jun 9 08:18:23 UTC 2007

Steve Kostecke wrote:
> In which case you must ensure that these two servers stay in
> relatively close synchronization.
> With only two servers of equal strata the clients will not have a
> clear best choice. If the servers drift too far apart you could have
> cases of inter-client offsets exceeding your stated accuracy.


I would be inclined to add two Internet-connected servers as NTP servers 
(they can also sync to the GPS/CDMA boxes), so that the clients point to 
four servers, all local.  Even if both the stratum-1 references fail, you 
still have good timekeeping.  These extra servers can be existing servers, 
nothing special, although perhaps ones with a little spare network I/O 

Running Windows clients connected to a stratum 1 server I see well under 
100ms error:


Be sure to use a client NTP which includes the "Run the MMtimer 
continuously" fix, though, such as:


If you use the W32time (default Windows client), it only updates once 
every few hours, which may not be good enough for you.

Remember to use iburst on the clients, so they sync more quickly when 
starting up.


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