What is subnet masking? What is it for?
One of the most difficult topics to understand about TCP/IP appears to be subnet masking. Many books on TCP/IP ignore it or give it only a paragraph or one page in a 500 page book. The few I've seen that do give subnetting serious attention fail to provide a good basic definition. Without a good definition, the difficulty of the material is magnified. I hope the definition linked above will provide you the insight you might otherwise miss.
The second link above began as an article written to help people prepare for Microsoft's TCP/IP certification exam, but it's been rewritten to generalize it a bit more for anyone who wants to figure out how subnet masking works.
The third link is a definition of IP Addressing, in response to requests from a few folks who were having trouble with that.
The fourth link discusses subnet masking in IPv6.
Copyright © 1999-2006 John Lambert, all rights reserved.
John is a premier field engineer with Microsoft.