Cisco router with dhcp configured inside

Unanswered Question
Feb 29th, 2008


I have a 2821 cisco router with dhcp configured inside. This works really fine but, even I have configured dns servers with dhcp, when a pc is configued to adquire ip lan address and dns servers.. this station does not works with internet, no dns internet name resolucion.


whats wrong?

Best regards

I have this problem too.
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Mohamed Sobair Fri, 02/29/2008 - 12:01


Have you set the gateway of the client in the DHCP config?

Does this router doing name resolution, I mean from the router, you could check there is reachability to the internet?

The DHCP service provided by the router has no impact of any internet reachability, unless the Internet is not reachable from the same router?



Richard Burts Fri, 02/29/2008 - 12:39


You make some good points for Edgar. I wonder whether the problem is name resolution or whether the problem is with Internet access. You ask whether the router can access Internet resources. I would suggest a slightly different version of that question. Not only can the router access Internet resources but more importantly can the clients access Internet resources if they do not need name resolution. On a client if you type the IP address of an Internet server into the browser rather than the name, can the client reach it?



edgar-quintana Fri, 02/29/2008 - 16:30


The problem is the name resolution.If I put manually a primary dns server and tcpip address dinamically, it works fine.

Router results:


Translating ""...domain server ( [OK]

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to, timeout is 2 seconds:


Success rate is 0 percent (0/5)


DCHP server has configured a default router wich is itself.

I do not know what more can I do...

Richard Burts Fri, 02/29/2008 - 17:31


I am a bit confused. Is vpn4 whose test result you have posted the router or an end station?

Also what you have posted does show that the name is resolved to an address. But then the attempt to ping fails. Which takes me back to the question I was attempting to raise in my previous post which is to determine whether there is a problem with name resolution or a problem with Internet access. These results look like the problem is with Internet access.

Can you clarify so we can understand better?



edgar-quintana Sat, 03/01/2008 - 02:43


This is my router configuration:

ip dhcp pool xxxx

import all


dns-server (ISP DNS server)

default-router cisco routers ip address)

netbios-name-server (locally ActiveDirectory domain address)

ip name-server

ip name-server

mahmoodmkl Sat, 03/01/2008 - 04:44


Can u verify that u have proper routes configured on u r router.First can u reach the next-hop which is u r ISP from the router.

And just exclude the IP address of the router from the DHCP Scope.



edgar-quintana Sat, 03/01/2008 - 05:19


DHCP ip spool is from 220 to 230 or 240, routers ip is out or range.

i have a pc with static lan ip...

PC ip :




And works really fine

"First can u reach the next-hop which is u r ISP from the router."

What this meaning? do ping from the router not a pc and ping a internet machine and resolve?


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