bash$ nslookup www.linuxnews.com -silent Server: 1.2.3.2 Address: 1.2.3.2#53 Non-authoritative answer: Name: www.linuxnews.com Address: 207.247.9.92
If this command gives you basically the same results, then your DNS server is working fine and you are connected to it. If it does not work, then you might need to check the DNS servers to see it they are correct. You can check your DNS settings using the commands linuxconf, netconf, or netcfg. All of the Domain Name Servers you use are also listed in your /etc/resolv.conf file.
bash$ cat /etc/resolv.conf domain cs.byuh.edu search cs.byuh.edu nameserver 1.2.3.2 nameserver 1.2.3.3
If this list does not look correct to you, or if there are no name servers listed, then that would be something that you need to take care of.
If you have an IP address, you can ping your gateway, you can get names back from the DNS, and still cannot talk to the outside world, then it is possible that the problem comes from your Internet Service Provider (ISP), there are two computers using the same IP address, or you might have some type of firewall problem.