Warning! Audit Deprecated
Information
RFC 5001 suggested a new EDNS0 option that is able to identify a DNS server with a Nameserver ID tag. NSID is a method to identify servers in an environment where there are multiple DNS servers sharing the same IP address. With the use of load balancing and other IP sharing mechanisms, it can become difficult to discern exactly which name server is responding to a particular query. NSID allows a name server to respond with identifying information. The ability to respond to NSID queries was added in BIND 9.5 to help ease the identification of DNS servers. The payload of the NSID can vary according to the wants and needs of the server's administrator. It can contain any string the administrator likes. It is recommended that NSID support be left off.
Rationale:
Enabling this can allow external parties to obtain information about the configuration and architecture of the DNS server. If it is found to be necessary to enable this service, then the identifying information should be generic. You should not use the server's geographic location, IP address or any other privileged information
Solution
Use the following in named.conf to explicitly disable NSID support:
server-id none;