Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. If you'd prefer to explore, try our test area to get started. And see here for current known issues.

New Member

Cisco 2514 Blocking DNS IP Question

Hello Everyone,

I have a Cisco 2514 that is using NAT

from Ethernet1 to Forward traffic to

Ethernet0 (my cable modem).

Ethernet0 obtain's it's IP via DHCP.

It also grabs the Nameservers from there.

My question is, the only way I can DNS

working is to use OpenDNS numbers which

are different from the name-servers my IP


I can't ping my DNS servers from my Router

or connection, but I can from a SSH connection

outside my network.

Is there some way my router is blocking traffic

to these servers?

Thanks in advance for any help that could

be provided.

Have a great day!

-Chris Barger

  • WAN Routing and Switching
Hall of Fame Super Silver

Re: Cisco 2514 Blocking DNS IP Question


It is possible that your router is blocking traffic to those DNS servers. You provided some helpful information but not enough for us to find the problem yet.

One of the possible issues could be an issue with routing on the router to outside destinations, or it could be an issue with the way that NAT is configured, or it could be that there is an access list on one of the interfaces of the router. Or it might be possibly an issue with the configuration of the default gateway on the PCs on your inside connection.

A good place to start is with the question of whether you can access resources in the Internet by IP address if you can not get to the DNS server to resolve the name? For example the IP address of is If you put that address into your browser do you get to

It would also be helpful if you would post the configuration of your router.



This widget could not be displayed.