Understanding IPv4 Subnetting in My Learning Journey

#networking #ipv4 #cybersecurity

Subnetting helps us divide a large network into smaller networks. This makes IP address management more efficient and improves network organization. One of the first things I learned was how to calculate the number of networks, number of usable hosts, and subnet masks.

Number of Networks = 2^n

Here, n is the number of bits borrowed from the host portion. The more bits we borrow, the more networks we can create.

Powers of 2 Chart

Number of Usable Hosts = 2^h − 2

Here, h is the number of remaining host bits. We subtract 2 because every subnet needs one network address and one broadcast address.

Ex: 192.168.1.0/25
If the original network is 192.168.1.0/24, changing it to /25 means we borrow 1 bit from the host portion.

Borrowed Bits = 25 − 24 = 1

Number of Networks = 2^1 = 2

This creates two subnets

192.168.1.0/25
192.168.1.128/25

Finding the Subnet Mask
The /25 means that 25 bits are used for the network portion and the remaining 7 bits are used for hosts.

he subnet mask in binary format

11111111.11111111.11111111.10000000

Convert binary to decimal

Binary Chart

11111111 = 255
11111111 = 255
11111111 = 255
10000000 = 128

/25 = 255.255.255.128

For the subnet 192.168.1.0/25

Subnet Mask: 255.255.255.128
Network Address: 192.168.1.0
Host Bits: 7
Total Addresses: 128
Usable Hosts: 126
Host Range: 192.168.1.1 – 192.168.1.126
Broadcast Address: 192.168.1.127

11111111 = 255

Learning subnetting can be challenging at first. However, these formulas and charts make it much easier to understand how IPv4 addresses are divided into networks and hosts.

I'm excited to continue learning networking and improve my understanding step by step.