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Subnet Calculator

Enter IP Address & Mask or CIDR:
Use IP & CIDR Netmask:
Or IP & Netmask:
Or IP & Wildcard Mask:
Address:   00000001
Netmask: = 2411111111.11111111.11111111.   00000000
Wildcard:   11111111
Network:   00000000(Class C)
Broadcast:   11111111
HostMin:   00000001
HostMax:   11111110
Hosts/Net:254( RFC-1918 Private Internet Address. )

Subnet Mask Generator Tutorial

The IP Subnet Mask Calculator enables subnet network calculations using network class, IP address, subnet mask, subnet bits, mask bits, maximum required IP subnets and maximum required hosts per subnet.

Results of the subnet calculation provide the wildcard mask, for use with ACL (Access Control Lists), subnet ID, broadcast address, the subnet address range for the resulting subnet network and a subnet bitmap.

What is Subnet?

A subnetwork, or subnet, is a logically visible subdivision of an Internet Protocol (IP) network. All computers that belong to a subnet are addressed with an identical common, most-significant bit-group in their IP address, which is called their routing prefix.

Breaking a network into smaller realms, a process called subnetting, may use an address space more efficiently, may enhance routing efficiency, or have advantages in network management when subnetworks are administratively controlled by different entities in the larger organization. Physical separation of network traffic may prevent excessive rates of Ethernet packet collisions in a larger network. The subnets may be arranged logically in a hierarchical architecture, partitioning the organization's network address space into a tree-like routing structure. Routers are used to interchange traffic between subnetworks; they constitute logical or physical borders between the subnets, and manage traffic between subnets based on the high-order bit sequence (routing prefix) of host addresses.

A routing prefix is the sequence of leading (most-significant) bits of an IP address that precede the portion of the address used as host identifier. Routing prefixes are expressed in CIDR notation. A routing prefix in CIDR notation is the first address of a network followed by the bit-length of the prefix, separated by a slash (/) character. For example, is the prefix of the IPv4 network starting at the given address, having 24 bits allocated for the network number, and the rest (8 bits) reserved for host addressing. The IPv6 address specification 2001:db8::/32 is a large network for 296 hosts, having a 32-bit routing prefix.

In IPv4 networks, the routing prefix is traditionally expressed as a subnet mask, which is the prefix bit mask expressed in quad-dotted decimal representation. For example, is the subnet mask for the prefix.