Missing the trailing dot in zone file

Missing the trailing dot in config authoritative name servers is a common mistake committed by network administrators. I admit that I always forget this important aspect.  As a reminder, I now jot down some easy reference to alert myself aware of this carelessness.

Forward lookup of mx for zome example.com

; zone example.com.

@  IN  MX 10  mailhost.example.com

[ the final part should be mailhost.example.com.]

becomes

@  IN  MX 10  mailhost.example.com.example.com.

Reverse lookup of 192.0.2.1 to produce host.example.com

; zone 2.0.192.in-addr.arpa.

1  IN  PTR    host.example.com

[ the final part should be host.example.com.]

becomes

1  IN  PTR    host.example.com.2.0.192.in-addr.arpa.

Keep the above in mind as much and as long as possible.