Check your DNS Server configuration ( BIND )

Check BIND – DNS Server configuration file for errors with named-checkconf tools

Check your bind configuration for errors?
# named-checkconf /etc/named.conf

You may want to chroot to directory so that include directives in the configuration file
# named-checkconf -t /var/named/chroot /etc/named.conf

If there is no output
# named-checkconf /etc/named.conf

Output

[ /etc/named.conf:58: open: /etc/named.root.hints: file not found ]

check my zone file configuration for errors?
syntax # named-checkzone {zonename} {filename}
command #named-checkzone nixcraft.com /var/named/zone.nixcraft.com
Output

[ok]

dig www.example.com
# simple host lookup
dig www.example.com a
# order is important
dig -t a www.example.com
# identified option format - order is not important
dig @ 208.77.188.166 www.example.com a
# use the dns at 208.77.188.166for the query
dig @ns1.example.com www.example.com a
# use the dns at ns1.example.com for the query
dig -x 208.77.188.166
# reverse map query - returns PTR RR