the problem could be everywhere...
- your network cable is connected succesfully
- your nic is setup succesfully
- your gateway is set correctly
- the router isn't blocking any request from your site
- the nameserver settings are correct
- you can ping the router (by ipaddress not name)
- you can ping anything outside (try google 126.96.36.199)
- in case you're using dhcp the lease time isn't to small
- in case you're using dhcp the ip address is resolved by the dhcp server
and so on ...
have a nice day