I got following error messages from /var/log/messages:

Oct 19 23:47:59 serverxx named[26830]: network unreachable resolving 'ns2.next-gen.ro/AAAA/IN': 2a03:5e80:0:4:192:162:16:18#53
Oct 19 23:47:59 serverxx named[26830]: network unreachable resolving 'ns1.next-gen.ro/AAAA/IN': 2a03:5e80:0:4:192:162:16:20#53
Oct 19 23:47:59 serverxx named[26830]: network unreachable resolving 'ns2.next-gen.ro/A/IN': 2a03:5e80:0:4:192:162:16:20#53
Oct 19 23:47:59 serverxx named[26830]: network unreachable resolving 'ns2.next-gen.ro/AAAA/IN': 2a03:5e80:0:4:192:162:16:20#53
Oct 19 23:47:59 serverxx named[26830]: network unreachable resolving 'ns2.next-gen.ro/A/IN': 2a03:5e80:0:5:193:230:31:230#53

Solution

Login to SSH using as root user.

Open the BIND parameters file in the text editor. Add the OPTIONS=”-4″ parameter at the end of the file.

vi /etc/sysconfig/named

Save the file and restart BIND. Type the following command to restart BIND server

service named restart