Common IPv4 address classes and their ranges

IPv4 addresses are the foundation of internet communication, and understanding their structure is crucial for networking professionals. In this blog post, we will discuss the common IPv4 address classes, their ranges, and characteristics. We will also explore the differences between Class A, B, C, D, and E addresses, and how they are used in networking.

Table of Contents

IPv4 Address Overview

IPv4 addresses consist of 32 bits, which are represented in dotted decimal notation as four octets separated by periods (e.g., 192.168.1.1). Each octet ranges from 0 to 255, resulting in approximately 4.3 billion possible IPv4 addresses. To manage IP address allocation and routing, IPv4 addresses are divided into classes, each with a specific range and purpose.

Class A Addresses

Class A addresses have a range of 1.0.0.0 to 126.255.255.255. The first octet represents the network portion, while the remaining three octets represent the host portion. Class A addresses are used for large networks with a vast number of hosts, as they can accommodate over 16 million unique host addresses per network. The leading bit in a Class A address is always 0.

Class B Addresses

Class B addresses range from 128.0.0.0 to 191.255.255.255. The first two octets represent the network portion, and the last two octets represent the host portion. Class B addresses are suitable for medium-sized networks, as they allow for up to 65,534 unique host addresses per network. The leading two bits in a Class B address are always 10.

Class C Addresses

Class C addresses have a range of 192.0.0.0 to 223.255.255.255. The first three octets represent the network portion, and the last octet represents the host portion. Class C addresses are designed for small networks, supporting up to 254 unique host addresses per network. The leading three bits in a Class C address are always 110.

Class D Addresses

Class D addresses range from 224.0.0.0 to 239.255.255.255 and are reserved for multicast groups. Unlike the previous classes, Class D addresses are not used for standard unicast communication between hosts and networks. The leading four bits in a Class D address are always 1110.

Class E Addresses

Class E addresses have a range of 240.0.0.0 to 255.255.255.254 and are reserved for experimental and future use. They are not currently assigned to any specific purpose or function. The leading four bits in a Class E address are always 1111.

Address Class Summary

To summarize, IPv4 addresses are divided into five classes, each with a specific range and purpose:

Understanding the different IPv4 address classes and their ranges is essential for network administrators, as it helps them plan and manage IP address allocation and routing. Familiarity with these classes can also assist in troubleshooting network issues and recognizing the appropriate address type for a given network scenario.

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5 min. read
17 Oct 2022

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