CertiGuide to A+ (A+ 4 Real)  9  Chapter 13: Basic Networking Terminology       9  OSI Reference Model and Networking Protocols and Technologies            9  Layer 3 - Network Layer

Class B 1 Subnet Mask

An example of a Class C IP address is 192.98.13.124. The first three octets identify the network number assigned by ARIN. The internal administrators of the network assign the remaining 8 bits Class C IP addresses always have values ranging from 192 to 223 in their first octet. Every network that uses a Class C IP address can have assigned up to 254 possible IP addresses to devices that are attached to its network

Subnet addresses include the Class A, Class B, or Class C network portion, plus a subnet field and a host field. The subnet field and the host field are created from the original host portion for the entire network. The ability to decide how to divide the original host portion into the new subnet and host fields provides addressing flexibility for the network administrator. To create a subnet address, a network administrator borrows bits from the original host portion and designates them as the subnet field.

The primary reason for using subnets is to reduce the size of a broadcast domain. Broadcasts are sent to all hosts on a network or a subnetwork. When broadcast traffic begins to consume too much of the available bandwidth, network administrators may choose to reduce the size of the broadcast domain

Class B 1 Subnet Mask