IPv4 Subnet Calculator

IPv4 subnet calculator

The IPv4 subnet calculator divided the IP into the various components - network address, subnet mask, broadcast address, and host IP address range to IP network into subnetworks. The Cisco wildcard mask is the inverted network mask used in Cisco routers for access control lists (ACLs).

To calculate an enter the IP address, choose a prefix length and click "Get IP Info".
The information, such as network address, first address, last address, broadcast address, netmask, and total IPs will be displayed.

IP Class Address Range

• Class A - 1.0.0.1 to 126.255.255.254 (supports 16 million hosts on each of 127 networks).
• Class B - 128.1.0.1 to 191.255.255.254 (65,000 hosts on each of 16,000 networks).
• Class C - 192.0.1.1 to 223.255.254.254 (254 hosts on each of 2 million networks).
• Class D - 224.0.0.0 to 239.255.255.255 (address range reserved for multicast groups).
• Class E - 240.0.0.0 to 254.255.255.254 (reserved for future use, research and development purposes).

Subnet Mask Cheat Sheet

A quick reference for IPv6 Subnetting and Subnet masks.

Subnet Mask Definition

Every device has two IP addresses: one for the client or host and one for the server or network. A DHCP server or a manual configuration is used to assign IP addresses (static IP addresses).

The subnet mask divides an IP address into the host and network addresses, indicating which portion belongs to the device and the network. A gateway, sometimes known as a default gateway, is a device that links local devices to external networks.

When a local device wishes to transfer data to a device with an IP address on another network, it sends its packets to the gateway, relaying the data to its destination outside the local network.

CIDR Subnet Mask Notation

When translated to binary, the CIDR number originates from the number of ones in the subnet mask.

The number of bits available to the IP address is represented by the CIDR notation, which is essentially just shorthand for the subnet mask.
For example, the/24 in 192.168.0.101/24 corresponds to the IP address 192.168.0.101 with the subnet mask 255.255.255.0.

Compared to the traditional Classful addressing scheme, the CIDR IP addressing system allows for more flexible IP address allocation (A, B, C, D, and E). The Classful IP addressing system may be inefficient. It gives a network that only requires 15 IP addresses the minimum IP address allocation of 256 (Class C).

In 1993, CIDR was established to reduce the use of IPv4 addresses, which were quickly running out under the previous Classful IP addressing system that the internet was built on.

In IPv4 and, more recently, IPv6 routing, CIDR is employed. When setting addresses and networks, it is advised to use CIDR (Classless Inter-Domain Routing) notation rather than the usual subnet mask 255.x.x.x.x when configuring addresses and networks.