By default BIND will display its version number as a chaos type TXT record called version.bind .

host -t TXT -c CHAOS version.bind nameserver
Using domain server:
Name: nameserver
Address: ipaddress#53

version.bind descriptive text "version number here"

Hiding the version number will make a nameserver slightly less vulnerable to attacks from hackers. If a particular vulnerability for a specific BIND release is announced hackers may try searching numerous records until a a hit for the exact version is found. Hiding the version number protects the server from this.

Hide BIND Version Number

options {
    version "Not available";

A reload of the config required for the config change to take effect: sudo /etc/init.d/bind9 reload

Category:DNS Category:BIND