I‘d like to know what TCP and UDP ports need to be open for the Domain Name Service (DNS BIND server) to function properly under Linux, OS X and UNIX like operating systems?
You need to use the following TCP and UDP ports on servers:
- TCP port 53 – This is used to get when response data exceeds 512 bytes. The zone trasfer between master and slave is also done using TCP port 53.
- UDP port 53 – This is primarily used by clients to make dns queries which are less than or equal to 512 byes. If the DNS server response data exceeds 512 bytes, the UDP query will fail and client will retry using TCP port 53.