One of the most important skills you’ll need to master in networking—and for your CCNA exam—is IP addressing and subnetting. Many beginners find it confusing at first, but once you understand the basics, subnetting becomes an essential tool that makes your network more efficient and easier to manage.
In this post, we’ll break down IP addresses, subnet masks, and subnetting in a simple way, with examples you can practice on.
What is an IP Address?
An IP address (Internet Protocol address) is like the “phone number” of a device on a network. It allows computers, routers, and other devices to identify and communicate with each other.
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Example: 192.168.1.1 is a common private IP address.
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Each IP address has two parts:
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Network portion (which network it belongs to).
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Host portion (the specific device on that network).
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IPv4 vs IPv6
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IPv4: Uses 32-bit addresses (e.g., 192.168.10.1). Limited to about 4.3 billion addresses.
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IPv6: Uses 128-bit addresses (e.g., 2001:0db8:85a3::8a2e:0370:7334). Provides trillions of unique addresses for the future.
What is a Subnet Mask?
A subnet mask divides an IP address into its network part and host part. For example:
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IP Address: 192.168.1.10
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Subnet Mask: 255.255.255.0
This tells the network that the first three octets (192.168.1) are the network, and the last octet (.10) is the host.
What is Subnetting?
Subnetting is the process of dividing one large network into smaller, more manageable networks (called subnets). This improves efficiency, reduces congestion, and enhances security.
Example:
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Original Network: 192.168.1.0/24
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Subnetted into:
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192.168.1.0/26 (64 addresses)
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192.168.1.64/26 (64 addresses)
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192.168.1.128/26 (64 addresses)
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192.168.1.192/26 (64 addresses)
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Why is Subnetting Important for CCNA?
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Efficient Use of IP Addresses – Prevents wasting addresses.
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Better Security – Separates departments (HR, Sales, IT) into their own subnets.
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Improved Performance – Reduces network congestion.
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Troubleshooting – Helps isolate problems quickly.
Quick Tips to Master Subnetting
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Memorize subnet mask values (/24, /26, /30, etc.).
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Practice using binary to decimal conversions.
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Use online subnet calculators for practice but learn to calculate manually for the CCNA exam.
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The more you practice, the faster you’ll get.
Final Thoughts
Subnetting may seem tricky at first, but it’s one of the most valuable skills you’ll gain while preparing for your CCNA certification. By practicing daily and working with subnetting problems, you’ll build the confidence needed not only to pass the exam but also to design and troubleshoot real-world networks.
So, grab a notebook, practice some subnetting questions, and watch as it all starts to click!