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ccna lab - can ping default gtwy from any rtr in lab but nt outside


I have 4 routers connected via serial dce/dte cables. from any of the rtrs I can ping any interface including the 2 1900 switches that are trunked together. I cannot ping beyond the dflt gtwy. with my nic pluged int either switch i can surf. why can't I ping yahoo or google from any of the routers?

5 Replies 5


It is difficult to say not knowing the exact configuration but maybe this will help.

Do all the routers have a default route to the internet? Either from a routing protocol or static.

If you are using "default-gateway X.X.X.X", this will not work. (The router uses its routing table)

Is "ip classless" configured?

Also - by default, if a ping is sent from a router it will use it's outgoing interface as the source of the packet. I assume you are NATing or something to the Internet. Does the Internet router or NATing device know that these networks exist and how to get to as well as NAT them?

These are all things to check.

I am using eigrp on the routers, do not have a default gateway set in the routers, I connect to the internet through a linksys router provided by my ISP. I assume it does the nat, pat. The cisco rtrs have only 1 ethernet each,I have one that connects to the aui on the 1900, port 25; port 27 on 1900 is where my linksys plugs in. the other switch is connected via trunk port 26. I can surf when I plug into either switch on any port. telnet into any cisco rtr can ping default gtwy but not beyond. If I enter say, It resolves to the Ip address but no success.

Thanks for responding!

I assume then that the ethernet interfaces on the routers are on the same subnet as the private LAN interface of the Linksys.

Do the routers have default routes configured? Assuming the Linksys inside IP address is then the routers would need "ip route" configured.

No. I don't have anything in it. since the pings to default were good through all routers and switches, I figured it was right.

the default gtwy on my isp rtr is and that rtr is configured to issue dhcp starting at 100. I have e0 set as thanks much for helping me out here! Will try the command string list by you; adjusted for my default, tonight. If she works I'll definetly rate it for you. thanks again.

As is evident I'm just learning and when I had tried entering a default command originally, I did it wrong. I had used the wrong syntax. Thanks much.

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