No Answer with DIG
 

I setup a DNS and tried to dig it but the reply is
Query:1 Answer:0 Status:Servfail
whats this Servfail? I even looked at the logs and found no error. Even when i checked my /etc/named.conf and /var/named/for, /var/named/rev file using
#named-checkconf /etc/named.conf
and
#named-checkzone mydomain.com /var/named/for and /var/named/rev
and
#dnsdomainname
I found that they were correct. But i am unable to dig my nameserver using
#dig -x 202.78.173.26
or
#dig ns1.mydomain.com
or
#host -al 202.78.173.26

What could be the problem? Humble suggestions required.

First of all check /etc/resolv.conf and make sure that your nameserver is the first in the list ,or use "dig mydomain.com @ns1.mydomain.com" to use your dns for your queries.
Without config files it's difficult to try to find, what the problem is.
Note also that the following dig output (nxdomain):
means that most likely you're not authoritative to the reverse zone, unless you own hellorainbow.com. You must ask your ISP to delegate you the zone for the subnet you own.

Ok thanx i got the answer. Its the ISP who is being digged.
Thanx for the suggestion.