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TechKnowSurge Catalog Videos DEMO: Network Addresses
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DEMO: Network Addresses

A network address is the first address in an IP range and identifies the network itself rather than any individual host. Understanding how to derive a network address from any given IP requires knowing the address class and which octets represent the network versus host portions.

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About this video

Every IP network is identified by a network address, which is the first address in the network's range. This address is reserved — it cannot be assigned to any host — and it serves as the logical identifier for the network itself. When devices on different networks need to route traffic between each other, the network address is what distinguishes one network from another, making accurate identification essential for proper routing. Deriving the network address from any given IP address depends on the address class. Class A addresses use the first octet as the network portion, leaving the final three octets for hosts, so the network address zeros out those last three octets. Class B addresses split the work across the first two octets for the network and the last two for hosts, and Class C addresses assign the first three octets to the network with only the final octet identifying individual hosts. In each case, the network address is produced by taking the network portion of the IP and setting all host bits to zero. For example, the Class C address 192.168.1.152 has a network address of 192.168.1.0, while the Class B address 132.222.11.23 resolves to a network address of 132.222.0.0. Recognizing the class of an address and correctly separating the network and host portions is a foundational skill in IP addressing, directly supporting subnetting, routing, and network design work that builds on these concepts.

What you'll learn

What's covered

Network Address

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.
CompTIA A+ Core 1
2.6 Compare and contrast common network configuration concepts.

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.
Subnet Mask
A 32-bit number that divides an IP address into network and host portions.
Network Address
The first address in an IP network range that identifies the network itself and cannot be assigned to a host. It is formed when all host bits are set to zero.
Classful Addressing
An early IPv4 addressing scheme that divided the address space into fixed classes (A, B, and C for hosts; D for multicast; E reserved) based on the leading bits of the address, with each class defining a fixed boundary between the network and host portions. Classful addressing was replaced by CIDR because it wasted large blocks of address space.
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

What a Network Address Is

In the last couple of lessons we identified the network portions and the host portions of our IP addresses. Now we're going to discover something called a network address. Let's talk about what a network address is, and then figure out what the network address is for each one of the networks that we have, or for an IP address within a network.

Back to our network topology. Here's our corporate network right here, and we've got it broken down into smaller networks. Right here we have some sort of network -- perhaps this is the headquarters office -- and this is perhaps a satellite office right here. So we've got these different networks that are out there. They have to be within a different range for us to be able to send traffic back and forth throughout here.

You'll notice that I'm using the 192.168, that is a Class C, so the first three octets of both of these ranges are the network portion. The network portion has to be different for all of my corporate network to be able to route traffic across here. Then we have the host bits, which is the last octet.

So what we need to do is assign a network out here. This is the network over here; we assigned a range for the network over here. And then somehow we distribute IP addresses for each of the hosts. Maybe this is dot five, this is dot six, maybe this is dot 152, maybe this is 153, and we assign different addresses to all of these devices that are on there.

This device right here has an address of 192.168.0.5. That is the address of that machine right there. But we also have this right here: 192.168.0.0. That is what we call a network address. A network address can't be assigned to a host on the network. The network address is the first of the range -- the first address of a range is the network address, and it cannot be used on any other device.

Finding the Network Address of an IP

So what we need to do is, when we have an IP address, be able to identify what the network address is for that IP address.

An example is, if I see 192.168.1.152, I can recognize that a 192 is a Class C, so the first three octets are the network address and the last octet is the host address. From that information I can determine that the first host of this network is a dot zero, so my network address is 192.168.1.0.

Working Through Examples

Now it's your turn to practice this. Let's go through that process one more time.

I'm going to take a look at this first one here. It's 132.222.11.23. By referencing this chart over here, I see that it's a Class B. I know that the first two octets are the network address and the last two octets are the host portion. So if this is the first address of that range, I'm going to say 132.222 is the network portion of it, and the first address of the range is 0.0. So that is my network address there.

I'll do one more here. So I've got 18.125.8118.44. It is a Class A, so I know that the first octet here is the network, and then if I zero out all the hosts, the first address of the range is 0.0.0.0 -- excuse me, I said one too many zeros there, but you get the point.

Go ahead and go through the rest of this, and then you can check your answers. Let's see how we did. I'm going to pull up the answers here, and then check your answers.

I hope you did well with that and identified the correct network address. Make sure you get this down. If you need to practice more, go ahead and practice more, because this is going to be something critical for you to really understand.

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