Billion Electric Company 30 user manual D.1.1.2 Subnet Addressing, D.1.1.3 Private IP Addresses

back slash (/). For example, a typical Class C address could be written as 192.168.234.245/24, which means that the net mask is 24 ones followed by 8 zeros. (11111111 11111111 11111111 00000000).

D.1.1.2 Subnet Addressing

Subnet addressing enables the split of one IP network address into multiple physical networks. These smaller networks are called subnetworks, and these subnetworks can make efficient use of each address when compared to needing a different network number at each end of a routed link. This technique is especially useful in smaller network environments, such as small office LANs.

A Class B address provides 16 bits of node numbers, which enable 65,536 nodes. Since most organizations don’t require such a large number of nodes, the free bits can be reassigned with subnet addressing.

Multiple Class C addresses can be made from a Class B address. For example, the IP address of 172.20.0.0 allows eight extra bits to use as a subnet address, since node addresses are limited to a maximum of 255. The IP address of 172.20.52.212 would be read as IP network address 172.20, subnet number 52, and node number 212.

Besides extending the number of available addresses, this technique also allows a network manager to design an address scheme for the network by using different subnets. This can be useful when trying to distinguish other geographical locations in the network or other departments in the organization.

D.1.1.3 Private IP Addresses

When isolated from the Internet, the hosts on your local network may be assigned IP addresses with no conflicts. However, the Internet Assigned Numbers Authority (IANA) has reserved several blocks of IP addresses for private networks. These include:

10.0.0.0- 10.255.255.255

172.16.0.0- 172.16.255.255

192.168.0.0 - 192.168.255.255

When assigning IP addresses to your private network, be sure to use IP addresses

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