Class And Networks

IP addresses are broken into 4 octets (IPv4) separated by dots called dotted decimal notation. An octet isa byte consisting of 8 bits. The IPv4 addresses are in the following form:

192.168.10.1

There are two parts of an IP address:

• Network ID
• Host ID

The various classes of networks specify additional or fewer octets to designate the network ID versus thehost ID.

When a network is set up, a netmask is also specified. The netmask determines the class of the networkas shown below, except for CIDR. When the netmask is setup, it specifies some number of mostsignificant bits with a 1's value and the rest have values of 0. The most significant part of the netmaskwith bits set to 1's specifies the network address, and the lower part of the address will specify the hostaddress. When setting addresses on a network, remember there can be no host address of 0 (no hostaddress bits set), and there can be no host address with all bits set.

Class A-E networksThe addressing scheme for class A through E networks is shown below. Note: We use the 'x' characterhere to denote don't care situations which includes all possible numbers at the location. It is many timesused to denote networks.