IPv4 Address Class Ranges

IPv4 addresses are divided into five classes, each with a specific range and purpose. Here are the details:

Class A:

• Range: 1.0.0.0 to 126.0.0.0
• Purpose: Designed for very large networks.
• Private Range: 10.0.0.0 to 10.255.255.2551.

Class B:

• Range: 128.0.0.0 to 191.255.0.0
• Purpose: Suitable for medium-sized networks.
• Private Range: 172.16.0.0 to 172.31.255.2551.

Class C:

• Range: 192.0.0.0 to 223.255.255.0
• Purpose: Used for small networks.
• Private Range: 192.168.0.0 to 192.168.255.2551.

Class D:

• Range: 224.0.0.0 to 239.255.255.255
• Purpose: Reserved for multicast groups.

Class E:

• Range: 240.0.0.0 to 255.255.255.255
• Purpose: Reserved for experimental use.

These classes help organize and allocate IP addresses efficiently across different types of networks.

You can use Class A, B, or C on your internal network regardless of its size. These are just recommendations.

This is covered in A+, Network+, and Server+.

 RFC 1918 Addresses

RFC 1918 addresses are IP addresses reserved for private use within internal networks. They are not routable on the public internet, meaning they are used exclusively within private networks. The primary purpose of these addresses is to alleviate the shortage of IPv4 addresses and enhance network security by isolating internal network traffic from the public internet.
 
RFC 1918 specifies three ranges of IPv4 addresses for private use:
 

Class A Private:
10.0.0.0 to 10.255.255.255 (10.0.0.0/8)

Class B Private:
172.16.0.0 to 172.31.255.255 (172.16.0.0/12)

Class C Private
192.168.0.0 to 192.168.255.255 (192.168.0.0/16)

These address ranges are commonly used in home, office, and enterprise networks. Devices within these networks can communicate with each other using these private IP addresses but require a Network Address Translation (NAT) device to communicate with external networks or the internet.