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

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