Performing a DNS lookup with dig results in this What might be wrong in the zone
definition?

A.
There’s no “.” after linuserv.example.net in the PTR record in the forward lookup zone
file.

B.
There’s no “.” after linuserv in the PTR record in the forward lookup zone file.

C.
There’s no “.” after linuserv.example.net in the PTR record in the reverse lookup zone
file.

D.
The “.” in the NS definition in reverse lookup zone has to be removed.

E.
Nothing. All seems to be good.