Sams Teach Yourself TCP/IP in 24 Hours, Fifth Edition

Hour 5. Subnetting and CIDR

What You’ll Learn in This Hour:

• Subnetting

• Subnet masks

• CIDR notation

Subnetting evolved as a means for using IP addressing to break up a physical network into smaller logical entities called subnets. Later developments, such as classless interdomain routing (CIDR, discussed at the end of this hour) and IPv6 (see Hour 13, “IPv6: The Next Generation”), have reduced the need for the classical approach to subnetting, but these later techniques borrow from the basic subnetting principles, and no discussion of TCP/IP is complete without a description of subnetting. This hour addresses the needs and benefits of subnetting and describes the steps and procedures you should follow to generate a subnet mask.

At the completion ...