A subnet is an address space of IP addresses, which in turn is split into smaller dimensioned address spaces. Thus, the subnet becomes a part of a network in which all IP addresses use the same network address. If all subnets are connected to a router, a large network is created.

When are subnets used[edit]

Subnets are used when the network load is to be reduced and distributed better. In this case, several IP addresses are grouped within a subnet. Data packages do not have to go through several stations until the desired address is reached. All you need is the network address. Consequently, subnets are used whenever multiple hosts or devices are to be connected to a large network.

The subnet mask[edit]

An IP address consists of two parts, a network address and a host address. The subnet mask is used to determine at which point the two parts of an IP address is separated. For this reason, the subnet mask is as long as the IP address. One device is used for the network and the other is the device used in the network (host). Thus, different hosts (computers) can be addressed within a subnet. The number of these network stations (hosts) depends on the network address and the subnet mask. Within an IP address range, the first as well as the last IP address must remain reserved for network and broadcast addresses.

How many hosts can be used per address space[edit]

Looking at the IP address space from to with the predetermined subnet mask or / 24; represents the network address and represents the broadcast address. In this case, another 254 IP addresses could be assigned to hosts.

Network address:
Subnet mask: or / 24
Subnet mask Bit notation: 1111 1111. 1111 1111. 1111 1111. 0000 0000
Address range: -
Broadcast address:
Host range: -

How to check if two hosts are on the same network[edit]

To check whether Host1 ( / 24) and Host2 ( / 24) are on the same network, proceed as follows: First, write the IP address as well as the subnet mask associated with it in bit-writing. The next step is to find the common “1” of host and subnet mask.

Host1: 	1100 0000 1010 1000 0000 0000 0010 0010
Subnet Host 1: 	1111 1111 1111 1111 1111 1111 0000 0000
Identical1: 	1100 0000 1010 1000 0000 0000 0000 0000
Host2: 	1100 0000 1010 1000 0000 0000 0010 0010
Subnet Host2: 	1111 1111 1111 1111 1111 1111 0000 0000
Identical2: 	1100 0000 1010 1000 0000 0000 0000 0000

In this case, “Identical1” and “Identic2” are exactly the same. This suggests that Host1 and Host2 are on the same network.

Subnetting and SEO[edit]

Many SEOs try to do link building with satellite sites. They also use subnetting and create different projects with different IP addresses in different subnets. Although the domains then have different IP addresses, they have the same network address. These pages are thus quickly revealed by search engines as a link network. The same applies to the link exchange with other webmasters. If you discover that a website offering to exchange links with you, (even though it has a different IP address) belongs to the same network, you should refrain from exchanging.