DNS Server

[sgalarza]

Our organization has DNS servers setup on our Windows Servers, my question is, is it necessary to have the DNS entries on our cisco devices? 

example: ip name-server X.X.X.X 

Or do we need it in our DHCP pool, or do we need it at all?  I'm just wondering if it's necessary to have the entry in the device at all.

Thanks,

Steve

[Jon Marshall]

You need DNS server entries in your DHCP pool using the "dns-server ..." configuration for your end clients to be able to resolve hostnames to IP addresses etc. assuming you are using the router for DHCP.

If you are using servers for DHCP as well as DNS then obviously you don't need the above.

The "ip name-server .." command is used if you want the router to be able to resolve hostnames to IP addresses which can be of use if, for example, you wanted to connect from a router to another device using a hostname instead of an IP address.

Jon

[sgalarza]

Thanks Jon,

We do use our routers for DHCP and we do have the DNS entries in the pool.  We have ip name-server entries (same entries as the DHCP pool) on each router as well.  So what you're saying is the ip name-server isn't absolutely necessary for the end users workstations, the entries in the DHCP pool resolve names for the end users.  Correct?

[Jon Marshall]

Correct, it is the entries in the DHCP pool configuration that the end clients use.

If you removed the "ip name-server ..." command it would not affect the end clients only the router's ability to resolve names itself although I am not suggesting you do that without understanding why it is there at the moment.

Jon

[sgalarza]

We added the ip name-server entries ourselves but when I try to ping google.com it says 

Unrecognized host or address, or protocol not running.  That's why I was questioning the ip name-server command.  Any thoughts as to why I'm getting that message.  Our DNS servers are internal.  Thanks

[Jon Marshall · Accepted solution]

Do you have any acls in place, can you ping the DNS server from the router ?

Presumably you have not disabled "ip domain-lookup", it should be on by default.

Jon

[sgalarza]

Ah Ha!! Jon, it was the ip domain-lookup command.  I appreciate your insight.  Thanks again.

[Jon Marshall]

No problem, glad to have helped.

Jon