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DEMO: IP Address Classes

IP address classification is a foundational networking skill covered through hands-on practice identifying which class—A, B, or C—a given address belongs to based on its first octet range. Accurate and fast classification is essential for understanding how networks are structured and addressed.

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About this video

IP address classification is one of the most fundamental skills in networking, and the ability to identify a class quickly and accurately is essential for everything from subnetting to network design. Every IPv4 address belongs to a class—most commonly A, B, or C—and that class is determined entirely by the value of the first octet. Each class maps to a specific numeric range, so recognizing where a given octet value falls within those ranges is all that is required to make the determination. This content walks through the classification process using concrete IP address examples, demonstrating how to apply the octet ranges to arrive at the correct class. For instance, a first octet value of 152 falls between 128 and 191, placing it in Class B. Learners are given the opportunity to work through additional examples independently before reviewing the correct answers, reinforcing both accuracy and speed. Though the classification task itself is straightforward, consistent mastery of it is critical. IP class identification appears repeatedly across networking topics, and building fluency now ensures a stronger foundation for more advanced concepts in addressing, routing, and network segmentation.

What you'll learn

What's covered

IP Address Classes

Aligned to

CompTIA Network+
1.7 Given a scenario, use appropriate IPv4 network addressing.
Cisco CCNA
1.6 Configure and verify IPv4 addressing and subnetting
Cisco CCST Networking
2.2 Identify IPv4 addresses and subnet formats

Key terms

IP Address
A numerical label assigned to each device connected to a network that uses the Internet Protocol.
Internet Protocol
IP
The principal communications protocol for routing packets across network boundaries.
Address Class
A categorization system for IPv4 addresses divided into classes (A, B, C, D, E) determined by the value of the first octet, which defines the network and host portions of the address.
Octet
One of the four 8-bit sections of an IPv4 address, each separated by a dot in dotted decimal notation and representing a decimal value from 0 to 255. For example, in 192.168.1.1, the four octets are 192, 168, 1, and 1.

Transcript

It's going to be really important that you can quickly and accurately determine what class a certain IP address is in. It's going to be very critical from here on out to be able to identify those classes. So I'm going to present you with a task, figure out the task, and then see how well you did and how close you were to the actual answer.

Determining the Class from the First Octet

As we saw in our last video, it's really the first few bits that determine what class an IP address is going to be in. So really it's the first octet. We can look at the first octet and determine what range it falls into, and therefore what class it falls into.

In this example right here, this is 152, so I'm going to look at my chart over here. Where does 152 fall into? Well, it's between the range of 128 and 191, so this is a Class B. I'll write Class B in here.

To make sure that you have this down, go through these different IP addresses and determine all of the classes, then find out if you got the right answer.

The Answers

Let's take a look at the answer here. There are the answers here. Again you can check your work to make sure that you're accurate.

Great, hopefully you did that really well. It's not really a complicated task, but it's a very critical task moving forward, so make sure you have this down. If you don't, you can practice it more and get really familiar with this, because we will be using this a lot.

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