DNS resolves addresses but I can't ping them

[vanalstine82731]

We are using a Cisco Catalyst 3925 running IOS 15.1 (R1) with an integral ES2-48 switch (S1) module in a lab environment. The modemis provided by Comcast. Consoling into R1 I can resolve domain names and ping them with no issues. However, while the Server 2012 machine correctly resolves domain names I cannot ping those addresses from the server. For example, it will resolves google.com (say) and provide the correct IP address but I can't ping it from the server.

Attached is the config files for the router and switch, as well as a diagram of our lab setup. Any help or suggestions is greatly appreciated.

[Jon Marshall]

It is probably because the modem does not have a route back to the 10.0.10.0/24 subnet with a next hop IP of 10.1.10.2. 

So add that route to the modem and make sure you have also setup NAT for that subnet on the modem. 

Alternatively you could NAT all the 10.0.10.x IPs to 10.1.10.2 on your router and then the modem would not need anything adding. 

Jon

[vanalstine82731]

Thanks. I added a route to Comcast router with no effect. Also traded to a external IP direct on G0/0 with bypassing the Comcast router (i.e. true bypass.) Problem still exists.

[Jon Marshall · Accepted solution]

Try this -

int gi2/0.100

ip nat inside 

int gi0/1

ip nat outside 

access-list 101 permit ip 10.0.10.0 0.0.0.255 any

ip nat inside source list 101 interface gi0/1 overload

Jon

[vanalstine82731]

thanks!