IPv4 (Internet Protocol version 4) addressing is a fundamental aspect of networking that enables devices to communicate with each other over an IP network. It provides a unique numerical identifier to each device connected to a network, allowing data to be routed between them. Here's an overview of IPv4 addressing:

1. 32-Bit Address Format:

  1. IPv4 addresses are 32 bits in length, represented in dotted-decimal notation, where each octet (8 bits) is separated by a period. For example: 192.168.1.1.
  2. The 32 bits are divided into four octets, with each octet ranging from 0 to 255, inclusive.

2. Classes:

  1. IPv4 addresses are categorized into five classes: A, B, C, D, and E.
  2. Classes A, B, and C are used for host addresses, while classes D and E serve special purposes.
  3. Each class has a different range of assignable IP addresses based on the values in their first octet.
  4. Class A: 0.0.0.0 to 127.255.255.255 (with 0 as the first octet).
  5. Class B: 128.0.0.0 to 191.255.255.255 (with 128 to 191 as the first octet).
  6. Class C: 192.0.0.0 to 223.255.255.255 (with 192 to 223 as the first octet).

3. Public and Private Addresses:

  1. IPv4 addresses are further classified into public and private addresses.
  2. Public addresses are globally routable and can be used on the Internet.
  3. Private addresses are reserved for use within private networks and are not routable on the Internet.
  4. Three blocks of private addresses are reserved for use in private networks:
    1. Class A: 10.0.0.0 to 10.255.255.255 (with 10 as the first octet).
    2. Class B: 172.16.0.0 to 172.31.255.255 (with 172.16 to 172.31 as the first octet).
    3. Class C: 192.168.0.0 to 192.168.255.255 (with 192.168 as the first two octets).

4. Subnetting:

  1. Subnetting is the process of dividing a network into smaller sub-networks (subnets).
  2. It allows for efficient use of IP addresses and helps manage network traffic by logically segmenting the network.
  3. Subnet masks are used to identify the network and host portions of an IP address.

5. Default Gateway:

  1. The default gateway is the IP address of the router interface that connects the local network to other networks or the Internet.
  2. It is used to forward packets destined for remote networks or devices outside the local network.

6. IPv4 Address Resolution Protocol (ARP):

  1. ARP is used to map IPv4 addresses to MAC addresses on a local network.
  2. It resolves the layer 3 (IP) address to the layer 2 (MAC) address of a device on the same network segment.

IPv4 addressing is a foundational concept in networking, enabling communication between devices on local and wide area networks. Understanding IPv4 addressing is essential for network administrators and engineers to design, configure, and troubleshoot IP-based networks effectively.