Subnetting is a vital part of computer networking and understanding IP addressing. It helps to divide a network into smaller, more manageable parts, improving overall network performance. If you’re new to networking, subnetting may seem complex at first. But, this guide will help you understand subnetting from the basics.
What is an IP Address?
An IP (Internet Protocol) address is a unique numeric identifier that identifies every device on a network. There are two types of IP addresses – IPv4 and IPv6. However, IPv4 is the most commonly used address format with 32 bits, making it possible to create almost 4.3 billion unique IPv4 addresses.
An IPv4 address is represented in four parts, separated by a dot. Each part is a decimal number ranging from 0 to 255, and the IP address looks like this – XXX.XXX.XXX.XXX. For instance, 192.168.1.1 is an example of an IPv4 address.
What is Subnetting?
Subnetting is a way of dividing a network into smaller parts known as subnets. In larger networks, subnetting is used to improve network efficiency by breaking down into smaller parts and assign unique addresses to the network devices. The subnet mask is the device that tells one network and subnetworks apart. It is a 32-bit number that is used to divide the IP address into network and host parts.
The subnet mask is represented in the same format as an IP address, e.g., 255.255.255.0. The “255” part of the subnet mask indicates a network, while the “0” part indicates a host. Therefore, in a subnet mask of 255.255.255.0, the first three octets (or 24 bits) represent the network portion, and the final octet (or 8 bits) represents the host portion.
Why Subnetting is Important?
Subnetting is important because it allows network administrators to divide a network into smaller, more manageable parts, increasing efficiency and reducing network congestion. For example, a large network with multiple subnets can help to prevent a broadcast from being sent to all devices on the network and prevent network bottlenecks.
Subnetting also helps to keep the network secure. By assigning unique IP addresses to different subnets, network administrators can limit unauthorized access, limiting potential security risks. It also improves the performance of the network, eliminating unnecessary traffic.
How to Subnet?
Subnetting is done using CIDR (Classless Inter-Domain Routing) notation, such as /24, /28, or /32. The notation indicates the subnet mask length in bits. For instance, /24 is equivalent to a subnet mask of 255.255.255.0 (24 bits), while /32 is equivalent to subnet mask 255.255.255.255 (32 bits).
To subnet an IP address, you need to understand binary arithmetic. To find the total number of subnets possible, take the number of bits in the subnet mask and count the number of 0’s. For example, a subnet mask of 255.255.255.0 has 8 0’s, which means there are 2^8 (256) subnets.
Conclusion
Subnetting is an essential part of IP addressing and helps to improve network efficiency, security, and performance. Whether you’re a network administrator or someone interested in understanding IP addressing, understanding subnetting is crucial. With this complete guide to subnetting, you can get started on your networking journey.