Subnet Mask

A subnet mask is an address composed of 32-bits expressed in numbers. It operates to identify the network address in an IP address. It is also intended to segregate the IP address into sub-categories like the host and network address.

A subnet mask determines the magnitude of a subnet. It also helps identify the source on the subnet whenever the user is given an IP address. It is referred to as a subnet “mask” because it literally masks away all the host bits. It reveals only the Network ID that launches the subnet.

The Host Address

The host is normally configured with an exclusive IP address and a subnet mask assigned to each interface that occurs on the network. Mostly, the host will possess only one network interface, which is why one IP address and one subnet mask is applied to it.

Hosts obtain the IP address and the subnet mask from DHCP(Dynamic Host Configuration Protocol). They may also be manually installed in the computer by the network administrator.

Why it is Needed

Using a subnet mask will define the IP subnet boundaries. Likewise, the interchange between the IP address and the subnet mask series adheres to a defined mathematical formula. Thus, the IP address will be a transparent identity, and the reserved and available parts can be seen by the host. Each network is usually configured with one IP address and subnet mask installed on a part of a network-capable calculator.

How the Mask Works

Every valid subnet mask consists of two parts:

1. The left side including all the mask bits set to ‘1’ is the extended network portion.

2. The right side including all mask bits, also set to ‘0’ is the host portion.

The existing computer network is divided by the mask into smaller networks or “subnets.” The effects of this splitting can be seen in the reduction of the broadcast domains because of lesser traffic. It also enables LANs of far distances to connect and communicate with each other. Moreover, the security aspect of the computer must be taken into account. Masking avoids the overlapping of LAN with one another.

It does not work like an IP address nor does it stay independently from that address. Instead, the subnet mask goes along with an IP address and works together with it.

Additional Reading on Subnet Mask