Unfortunately, there are so many ways networks can go wrong that they're hard even to categorize, much less describe and solve. With the development of wireless networks, potential problems have multiplied.
When diagnosing network problems, the first thing to remember is that most problems are physical. If you rush to change your networking software when the problem is just a hub without power, you could make things worse. As wireless networks have their own physical and software issues, we discuss this issue separately at the end of this annoyance.
This annoyance assumes you're using TCP/IP networking, which is the standard on the Internet. Because Unix was developed concurrently with the foundations of the Internet, and Linux is in many ways a clone of Unix, Linux is built for TCP/IP.
Some companies use other networking protocols to promote security or for legacy reasons. Linux can support other networking protocols, such as AppleTalk and IPX/SPX. For more information, see the applicable HOWTOs at http://www.anders.com/projects/netatalk and http://www.tldp.org/HOWTO/IPX-HOWTO.html.
After you fix a network problem, you may need to revise a configuration file to keep the problem from happening again the next time you boot. Generally, most modern distributions store these configuration files in the /etc/sysconfig/network or similar directories. If you have trouble finding the right file, Red Hat/Fedora, SUSE, and Debian all have ...