Update denied ?

[Veeraraju_Mareddi]

I am getting these errors in in syslog

Sep 26 10:08:24 nameserver /usr/local/sbin/named[10382]: client
172.18.1.75#1091: update denied
Sep 26 10:08:31 nameserver /usr/local/sbin/named[10382]: client
172.18.24.138#1367: update denied
Sep 26 10:09:28 nameserver /usr/local/sbin/named[10382]: client
172.18.57.185#5747: update denied
Sep 26 10:09:43 nameserver /usr/local/sbin/named[10382]: client
208.220.253.25#2513: update denied
Sep 26 10:09:45 nameserver /usr/local/sbin/named[10382]: client
208.220.253.25#2518: update denied
Sep 26 10:09:45 nameserver /usr/local/sbin/named[10382]: client
208.220.240.85#2491: update denied
Sep 26 10:09:45 nameserver /usr/local/sbin/named[10382]: client
208.220.240.85#2496: update denied

Can you please tell me what are these errors and how to get rid of it ?.

I see thousands of lines in syslog of same kind.

Thanks and Regards
Veeraraju

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