Slave DNS server configured in Plesk is not connected: rejected command channel message from 203.0.113.1#56373

Symptoms

• When trying to connect from master (203.0.113.2) to slave (203.0.113.3) with the command below:

  # rndc -b 203.0.113.2 -s 203.0.113.3 -p 953 -y "rndc-key" -c /usr/local/psa/var/modules/slave-dns-manager/slave_203.0.113.3.conf status

  The following error appears in the /var/log/messages on a slave DNS server:

  CONFIG_TEXT: ip-192.0.2.2 named[834]: rejected command channel message from 203.0.113.1#56373

Cause

DNS servers misconfiguration. Slave DNS server recognizes master as 203.0.113.1 instead of 203.0.113.2.

Resolution

1. Connect to the server via SSH
2. Open /etc/named.confin any text editor and add the reported in the error IP address to the list of the allowed name servers:
   

   CONFIG_TEXT: controls {
           inet 127.0.0.1 port 953
           allow { 127.0.0.1; 203.0.113.1; 203.0.113.2 } keys { "rndc-key"; };
   };