Vérificateur de Classe IP - Recherche de Classe A, B, C, D, E
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IP Class Checker

Check IP address classification, public/private status, and range info.

Guide Réseau

IP address classification is a fundamental concept in networking that organizes the vast IPv4 address space into distinct categories based on the address range and intended use. While modern networking has largely moved to Classless Inter-Domain Routing (CIDR) for efficient address allocation, understanding IP classes remains essential for network professionals. IP classes provide the historical foundation for how networks were originally designed, and they continue to influence subnetting, routing, firewall rules, and network documentation today.

IP address classification is a fundamental concept in networking that organizes the vast IPv4 address space into distinct categories based on the address range and intended use. While modern networking has largely moved to Classless Inter-Domain Routing (CIDR) for efficient address allocation, understanding IP classes remains essential for network professionals. IP classes provide the historical foundation for how networks were originally designed, and they continue to influence subnetting, routing, firewall rules, and network documentation today.

The Five IP Address Classes Explained

ipclass.h2a

ipclass.h2a2

Why IP Classes Still Matter Today

ipclass.h2b

ipclass.h2b2

Private vs Public IP Addresses Within Classes

ipclass.h2c

ipclass.h2c2

Special-Purpose IP Ranges

ipclass.h2d

ipclass.h2d2

Outils Connexes

CIDR CalculatorBinary IP CalculatorWildcard Mask CalculatorSubnet Calculator

Questions Fréquentes

What is IP class?

IP class is a method of categorizing IPv4 addresses based on their leading bits and first octet range. The original classful networking design divided the IPv4 address space into five classes: A, B, C, D, and E. Each class has a fixed default subnet mask and a specific number of network and host bits, determining how many networks and hosts each class can support. Classful addressing has largely been replaced by CIDR, but IP classes remain important for understanding legacy network configurations.

How to calculate IP class?

To calculate the IP class, look at the first octet of the IP address. Class A ranges from 1 to 126, Class B from 128 to 191, Class C from 192 to 223, Class D from 224 to 239 (multicast), and Class E from 240 to 255 (reserved). Addresses starting with 0 are reserved for default routes, and 127.x.x.x is reserved for loopback. You can also determine the class by examining the binary representation of the first octet: Class A starts with 0, Class B with 10, Class C with 110, Class D with 1110, and Class E with 1111.

What class is a 192.168 IP address?

A 192.168.x.x IP address belongs to Class C. The first octet 192 falls within the Class C range of 192 to 223. Class C addresses use a default subnet mask of 255.255.255.0 (/24), providing up to 254 usable host addresses per network. The 192.168.0.0/16 range is also part of the private IP address space defined in RFC 1918, making it the most commonly used range for home and small office networks.

What is C class IP?

A Class C IP address ranges from 192.0.0.0 to 223.255.255.255, with a default subnet mask of 255.255.255.0 (/24). Each Class C network supports up to 254 usable host addresses. The first three octets represent the network portion, and the last octet represents the host portion. Class C addresses are ideal for small to medium-sized networks such as office LANs, schools, and small businesses. The most recognizable Class C private range is 192.168.0.0/16.

Why use a 32-subnet mask?

A /32 subnet mask (255.255.255.255) is used to identify a single host. It means all 32 bits are network bits and there are zero host bits, so only one address exists in the subnet. /32 is commonly used for loopback interfaces on routers, for identifying a specific host in firewall rules and ACLs, and in cloud networking for assigning individual public IPs to virtual machines. It is also used in BGP route advertisements to advertise a single host route.