Classful IPv4 Addressing Demonstration

Classful addressing was the original method used to define network addresses in IPv4, before CIDR (Classless Inter-Domain Routing) was introduced. Enter an IPv4 address below to analyze its class and properties.

IP Address Analysis

IPv4 Address Classes

Class A

Range: 0.0.0.0 to 127.255.255.255

First Bit: 0

Format: N.H.H.H (1 byte network, 3 bytes host)

Default Subnet Mask: 255.0.0.0 (/8)

Networks: 126 (2^7 - 2, 0 and 127 reserved)

Hosts per Network: 16,777,214 (2^24 - 2)

Use: Very large networks

Class B

Range: 128.0.0.0 to 191.255.255.255

First Bits: 10

Format: N.N.H.H (2 bytes network, 2 bytes host)

Default Subnet Mask: 255.255.0.0 (/16)

Networks: 16,384 (2^14)

Hosts per Network: 65,534 (2^16 - 2)

Use: Medium to large networks

Class C

Range: 192.0.0.0 to 223.255.255.255

First Bits: 110

Format: N.N.N.H (3 bytes network, 1 byte host)

Default Subnet Mask: 255.255.255.0 (/24)

Networks: 2,097,152 (2^21)

Hosts per Network: 254 (2^8 - 2)

Use: Small networks

Class D

Range: 224.0.0.0 to 239.255.255.255

First Bits: 1110

Use: Multicast groups

Special: Not used for regular host addressing

Class E

Range: 240.0.0.0 to 255.255.255.255

First Bits: 1111

Use: Reserved for experimental purposes

Special: Not used in regular networks