Only used by master zones, this option allows you to specify a list of IP addresses that are to receive notify messages when a zone change occurs.
In most cases you should not need to set this, since the default is for all secondary name servers listed in the NS records of your domain to be automatically notified of any zone changes.
Valid values are one more IP addresses, semi-colon delimited. For example:
220.127.116.11; # Notify this address 18.104.22.168;22.214.171.124; # Notify all of these addresses