how to know what DNS server is being used

[Lane]

On Friday 27 October 2006 21:56, David Banning wrote:
> On my registrars site I have two DNS servers listing. How would
> I know that 1) both are working. 2) which one is being used.
>
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Depends mostly on where you are.

On server "A" you can check local dns resolution by doing:

cat /etc/resolv.conf

This should show you which servers are being queried for dns resolution.

You can check the ability of server "A" to resolve an address by doing:

nslookup www.yahoo.com

If the first line says:

Server:		"server a name"
Address:	127.0.0.1

on the first two lines, then that means that Server "A" is doing its own 
lookups, and probably using the contents of /etc/resolv.conf for stuff it 
doesn't know locally.

Still on server "A" you can check the ability of server "B" to resolve an 
address by doing:

nslookup www.yahoo.com server-b-address

And the top two lines will be the Server name and address of server "B" if 
server "B" knows how to do dns resolution.

You'd have to log into server b to cat /etc/resolv.conf, probably.

If you are on a Windows box you can use the "nslookup <address> <server a|b>" 
syntax to verify their abilities as well.  And, of course, "ipconfig /all" on 
windows will show you who he asks for dns resolution.

lane