Sometimes named.conf gets corrupted on cPanel server. Here is the way to fix that in cpanel servers. First of all move the corrupted named.conf using the following command:
mv /etc/named.conf /etc/named.conf.bak
Now simply execute the cpanel script to rebuild the named.conf
/usr/local/cpanel/scripts/rebuilddnsconfig
And restart the named service:
/etc/init.d/named restart
All should be fine again.