How Many IP Addresses Should a Router Have?

If you’re familiar with network and host portions in an IPv4 address, you’d know that each network running TCP must have a unique network number, and every machine on it must have a unique IP address. The bytes of IP addresses are further classified into two parts: the network part and the host part.

The network part specifies the unique number assigned to your network. It also identifies the class of the network assigned. Hostpart is a part of the IP address that you assign to each host. It uniquely identifies this machine on your network. Note that for each host on your network, the network part of the address will be the same, but the host part must be different.

But how do hosts know which portion of the 32-bit is network and which is host? That is the job of the subnet mask. In TCP, the parts of the IP address that are used as the network and host addresses are not fixed, so the network and the host addresses cannot be determined unless you have more information.

This information is supplied in another 32-bit number called a subnet mask. When an IP host is configured, a subnet mask is assigned along with an IP address. Similar to IPv4 address, the subnet mask is represented in dotted decimal format for ease of use. Like the IP address, the subnet mask is 32 bits long. The subnet mask signifies which part of the IP address is network and which part is host.

The subnet mask is compared to the IP address from left to right, bit by bit. The ones in the subnet mask represent the network portion, and the zeros represent the host portion. Note that the subnet mask does not actually contain the network or host portion as an IP address. It just tells the computers where to look for these portions in a given IPv4 address.

For example, let’s take an IP In this example, the subnet mask is slash 24, or you can call it as So, the subnet mask, if you convert it in binary, will be 24 ones and eight zeros. Lining up the IP address and the subnet mask together, the network and the host portion of the address can be separated.

The first 24 bits, the number of the ones in the net mask, are identified as the network address. With the last eight bits, the number of remaining zeros in the subnet mask, identified as the host address. This gives you the following network address in binary format, and the network address in decimal format will be The host address in binary format will be which if we convert to decimal, we will have a host address as 132.

In conclusion, routers should have at least one IP address per subnet, and each interface on a router should be configured with an IP address. Understanding subnetting and subnet masks is essential for proper TCP/IP networking.