[ntp:questions] Using two NTP Server: Bad?

Ben Rockwood benr at cuddletech.com
Thu Apr 21 01:14:36 UTC 2011

I've read in the past that clients should always have an odd-number of
NTP servers; 1 server or 3 servers but not 2.  If I recall the reason
was that clients could become "confused" and needs a tie breaker.

Question 1: I want to challenge this old assumption.  Is there truth to

In many environments there is a desire to have 2 NTP servers for
redundancy purposes, but not 3 due to limited resources.

Question 2: Furthermore, if you have 2 local NTP servers is it
preferable to have them sync off of different sources to avoid a client
syncing servers that are using the same reference clock?  ie: Is this bad?:

$ ntpq -pn
     remote           refid      st t when poll reach   delay   offset 
*    3 u  756 1024  377    0.494    0.596  
+    3 u  953 1024  377    0.135    0.144  

Thank you.


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