Why does ntpd fail with "no servers reachable" when I use exactly two NTP servers giving different time?

Solution Verified - Updated -

Issue

  • Red Hat Enterprise Linux system doesn't seem to be able to communicate with the NTP servers.
  • NTP clients not syncing with servers The logs show :

    ntpd[3162]: synchronized to 10.0.0.1, stratum 6 
    ntpd[3162]: synchronized to 10.0.0.2, stratum 6 
    ntpd[3162]: synchronized to 10.0.0.1, stratum 6 
    ntpd[3162]: no servers reachable    
    
  • ntpq output gives the following :

    # ntpq 
    ntpq> pe 
         remote           refid                  st t when poll reach delay   offset      jitter 
    ============================================================================== 
    x10.0.0.1            LOCAL(0)         6 u   49   64  377    1.103  -96.124   5.887 
    x10.0.0.2            LOCAL(0)         6 u   57   64  377    2.970    51.168   3.790
    

Environment

  • Red Hat Enterprise Linux 6
  • Red Hat Enterprise Linux 7
  • ntp package (any version)
  • There are exactly two NTP servers that are reachable
  • The two NTP servers don't give the same time as the offset is significantly different

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