IP Addresses and Address Classes
🔢 Address Splitting IP addresses are divided into two sections: the network ID and the host ID. For example, if we take the IP address 9.100.100.100, the network ID is the first octet, and the host ID is the second, third, and fourth octets.
🏢 Address Ownership Earlier, we mentioned that IBM owns all IP addresses where the first octet has a value of nine.
🌐 Address Class System The address class system defines how the global IP address space is split up. There are three primary types of address classes: Class A, Class B, and Class C.
Class A: The first octet is used for the network ID, and the last three octets are used for the host ID.
Class B: The first two octets are used for the network ID, and the second two octets are used for the host ID.
Class C: The first three octets are used for the network ID, and only the final octet is used for the host ID.
📏 Address Class Sizes Each address class represents a network of vastly different sizes.
Class A: 2^24 or 16,777,216 individual addresses.
Class B: 2^16 or 65,536 individual addresses.
Class C: 2^8 or 256 addresses.
👀 Determining Address Class You can determine the address class of an IP address by examining the first few bits:
If the very first bit is zero, it belongs to a Class A network.
If the first bits are 10, it belongs to a Class B network.
If the first bits are 110, it belongs to a Class C network.
💻 Address Ranges In dotted decimal notation, each octet in an IP address represents eight bits and can take a value between zero and 255.
Class A addresses: First octet values range from 0 to 127.
Class B addresses: First octet values range from 128 to 191.
Class C addresses: First octet values range from 192 to 223.
⚠️ Other Address Classes There are two additional address classes:
Class D: Addresses begin with the bits 1110 and are used for multicasting. Decimal values range from 224 to 239.
Class E: Addresses are unassigned and reserved for testing purposes. They encompass the remaining IP addresses.
🌐🔌📦🔒📨🔍💡
Last updated