IP addresses serve as unique identifiers for devices on a network, allowing data to be transmitted across the internet. The number of available IP addresses in a network prefix is determined by the length of the prefix. In this article, we will explore various network prefix lengths and the corresponding number of IP addresses they provide.

1. IPv4 Addressing:

IPv4 addresses are 32 bits long and are typically represented in decimal form with four sets of numbers (e.g., 192.168.1.1).

• /32 Prefix: A /32 prefix designates a single, individual IP address. It provides no additional IP addresses within the same subnet.

• /31 Prefix: A /31 prefix contains two IP addresses, typically used for point-to-point links. One address is assigned to each end of the link, and there are no usable IP addresses left for other devices.

• /30 Prefix: A /30 prefix contains four IP addresses, with two usable addresses. It is commonly used for point-to-point links or small subnets.

• /29 Prefix: A /29 prefix contains eight IP addresses, with six usable addresses. This is suitable for small networks.

• /24 Prefix: A /24 prefix contains 256 IP addresses, with 254 usable addresses. This is a common subnet size for home or small office networks.

• /16 Prefix: A /16 prefix contains 65,536 IP addresses. This size is suitable for larger organizations or service providers.

2. IPv6 Addressing:

IPv6 addresses are 128 bits long and are represented in hexadecimal form with eight sets of four characters (e.g., 2001:0db8:85a3:0000:0000:8a2e:0370:7334).

• /128 Prefix: A /128 prefix designates a single, individual IPv6 address, just like /32 in IPv4.

• /127 Prefix: A /127 prefix is used for point-to-point links in IPv6 and contains only two usable addresses.

• /126 Prefix: A /126 prefix contains four IPv6 addresses, with two usable addresses. It is used for point-to-point links or small subnets.

• /64 Prefix: A /64 prefix is the standard size for IPv6 subnets and contains an astonishing 18,446,744,073,709,551,616 (about 18.4 quintillion) IP addresses. This size allows for virtually limitless network growth and device connections.

• /48 Prefix: A /48 prefix contains 1,208,925,819,614,629,174,706,176 (about 1.2 undecillion) IP addresses. It is typically allocated to organizations and is suitable for global-scale networks.

The number of IP addresses in a network prefix is determined by the prefix length. IPv4 addresses have limitations due to their 32-bit structure, while IPv6 addresses offer an extensive pool of addresses due to their 128-bit structure. Understanding these different network prefix lengths is essential for IP address allocation, network planning, and efficient use of IP address resources in both IPv4 and IPv6 networks.