Subnets: An in-depth look at network infrastructure

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In the world of networking, effective IP address segmentation is a fundamental aspect of a secure and well-organized infrastructure. Subnets play a crucial role here. This blog post will walk you through the basics of subnetting, explain its importance, and show you how to use it effectively in your network infrastructure.

**1. What are subnets?

A subnet, short for subnetwork, is a division of an IP network into smaller, logical networks. This division enables efficient management of IP addresses and helps improve security and performance on a network.

**2. Why are subnets important?

  • Efficient IP address usage: Subnets allow for meaningful allocation of IP addresses by dividing the total amount of available addresses into smaller, manageable groups.

  • Security: By segmenting the network into subnets, security policies can be applied to specific areas. This minimizes the risk of security incidents affecting the entire network.

  • Performance Optimization: Subnets provide traffic control and can help optimize network performance by limiting traffic to specific segments.

**3. How does subnetting work?

  • IP Address Structure: IP addresses consist of a network prefix and a host prefix. By dividing the host prefix into subnets, specific areas of the network can be created.

  • Subnet mask: The subnet mask defines the range of IP addresses used for the subnet. It consists of a combination of network bits and host bits.

**4. Example application of subnets:

Let's say you have the IP address and want to split it into three subnets:

  • Subnet 1:
  • Subnet 2:
  • Subnet 3:

Each subnet has its own range of 64 IP addresses (from to, from to and from to This segmentation makes it easier to manage and organize devices on the network.

**5. Best practices for managing subnets:

  • Documentation: Maintain clear documentation about the structure and usage of subnets. This makes management and troubleshooting easier.

  • Plan for Growth: Consider future growth when determining subnet sizes to ensure easy scalability.

  • Clear security policies: Enforce clear security policies for each subnet to ensure protection against unwanted access.


The use of subnets is crucial for an efficient, secure and well-organized network infrastructure. This guide is designed to help you understand the basics of subnetting and how to optimize its use on your network. Use subnets as a powerful tool to maintain control of your network and build a robust, scalable infrastructure.

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Knowledge Base

Here we answer questions about server monitoring from Livewatch. If you have a question that we have not yet answered here, please contact us.

What is a subnet or subnet mask?

A subnetwork is a subset of a larger IP network that serves to divide the IP address space into logically isolated sections. Dividing a network into subnets provides several benefits, including more efficient address usage, better security, and improved network organization.

Here are the basic components of a subnet and how it works:

  1. IP Addresses: A subnet consists of a range of IP addresses. These addresses are selected from the network's entire IP address space. For example, a network might have the IP address range to

  2. Subnet mask: The subnet mask is a sequence of numbers that indicates which parts of the IP address represent the network portion and the host portion. For example, the subnet mask could be, meaning that the first three octets (192.168.1) represent the network portion and the last octet is reserved for the individual devices on the network.

  3. Logical Isolation: A subnet allows the IP address space to be logically isolated. Devices within the same subnet can communicate directly with each other as if they were on the same physical network. Devices on different subnets typically need to use a router to communicate with each other.

  4. Efficient Address Usage: Using subnets allows the available IP address space to be used more efficiently. Instead of using all IP addresses in one large range, smaller ranges can be reserved for specific parts of the network.

  5. Security: Subnets allow security policies to be applied at the subnet level. Traffic between subnets can be controlled through firewalls and other security mechanisms, improving the security of the network.

For example, a company might have one subnet for office equipment, another subnet for servers, and a third subnet for guest WiFi. This division helps organize network traffic, increase security, and optimize resource utilization.

What is a subnet?

A subnet is a way of dividing a larger network into smaller, logically isolated subnets. This is to manage network resources more efficiently, increase security and organize data traffic within the network.

A subnet consists of a group of IP addresses that are logically separated from each other. Within a subnet, devices can communicate with each other as if they were on the same physical network. Dividing a larger network into subnets has several advantages:

  1. Efficient address usage: By assigning subnets, IP addresses can be used more efficiently. Each subnet can have its own address range, which optimizes the allocation of IP addresses.

  2. Security: Subnets allow implementation of security policies at the subnet level. Traffic between subnets can be controlled through firewalls and other security measures.

  3. Network Traffic Organization: Subnets allow for better organization of network traffic. Limiting traffic to specific subnets can improve network performance.

  4. Scalability: Subnets facilitate network scalability. As a network grows, new subnets can be added without reconfiguring the entire network.

The IP addresses in a subnet usually share a common network prefix (subnet mask) that defines the range of IP addresses for that subnet. For example, a subnet could have the IP addresses in the range to, and the subnet mask could be, meaning the first three octets (192.168.1) represent the network portion and the last octet the host share.

Calculate subnet - calculation method

The subnet mask is used to divide an IP network into smaller subnets. It consists of a series of 32 bits divided into four octets of 8 bits each. The subnet mask is usually represented in decimal form, with each octet separated by a period (for example,

Here are the steps to calculate a subnet mask:

Decide how many subnets you need:

Consider how many networks or subnets you want to create from your overall network. The number of subnets determines the number of bits required for network division. Determine the number of bits for network sharing:

Count the number of bits needed to represent the number of subnets. These bits are later added to the subnet mask. Calculate the subnet mask in binary form:

Set the required bits in the subnet mask to 1 and pad the remaining bits with 0. Note that the subnet mask always starts with the left bits. For example, if you need 3 bits for network sharing, the binary form of the subnet mask is: 11100000 (for the first octet). Convert binary form to decimal form:

Convert each octet of binary form to the corresponding decimal number to represent the subnet mask in common decimal form. Here is an example: Suppose you want to divide a network into 8 subnets. You need 3 bits for network sharing.

Number of bits for network sharing: 3 bits Binary form of subnet mask: 11100000 (for the first octet) Decimal form of subnet mask: 224 (for the first octet) The full subnet mask for this example would then be

It is important to note that the subnet mask always begins with a series of 1 bits followed by a series of 0 bits. The network and broadcast address bits are always set to 0 and 1, respectively.