IP networks and subnets

Before moving on, a short review of typical IP subnetting terms and typical applications should help clarify the terms used in this book and will act as a refresher for those already versed in IP addressing.

A /24 designator placed after a network IP address in diagrams or device configurations is a Classless Inter-Domain Routing (CIDR) designator that indicates the following:

• The first 24 out of the 32 bits in the 4-byte IP address represents the network portion of any IP address on this network. This network is designated as 10.1.1.0 (the next /24 network would be 10.1.2.0, then 10.1.3.0, and so on).
• The last 8 bits of the 32-bit address can be used to give workstations, hosts, and other devices an IP address, with the following exceptions:
  • The first host address on this network is reserved as a network designator to build routing tables: 10.1.1.0 (typically called the loopback address)
  • The last host address on this network is reserved as an IP broadcast address: 10...