DNS testing

Applications IP Networking
1

Hi all,

Please can i know how to test an DNS server is working or not.
Please explain testing of newly setup DNS server with example.
DNS server is must for mailserver or not?

Thanks And Reg
Bache

2

an effective to way to test dns is to
use nslookup

the syntax is

nslookup domainname or ip address

examlpe is
nslookup www.yourdomainname.com
this will query yourdomainname dns and return an ip address.

or nslookup (ip address of your dns)
this will query yourdomainname dns using an ip address and return full domainname

dns is important for web base mail without it you will not be able to received or sent email outside your network or domain.

3

Is that necessory to give domain name and IP address to it?

4

man dig

5

Assuming you have a caching nameserver, as said above use dig
Test your nameserver using host or dig and querying redhat.com

)

From the above dig query you can see it took 42 msec to receive the DNS request. Now test out the caching ability of your nameserver by running dig again on the redhat.com domain.

We dropped from 42 msec to 1 msec after the previous DNS query was cached. Caching is working!