Q
Problem solve Get help with specific problems with your technologies, process and projects.

## Learn how to calculate IP addresses and subnet masks in this Q&A with Chris Partsenidis.

IP addressing and subnet masks are one of the most popular topics in the networking community simply because they can be very confusing and require some time to sink in.

While it's not possible to fully analyze the topic in one page, I'll give you a bit of information to start off with and some guidance to help you move deeper into the subject.

An IP address is an address that helps us uniquely identify a network device or host.

When configuring a computer with an IP address we define the logical network it is part of. A logical network is not something we can touch or see, but a term used to describe the way certain things are perceived by the computer or network device.

The IP address given to the computer tells it which network it belongs to, and how it will identify itself to the rest of the computers that are part of the same network. The subnet mask sets the network's boundaries.

IP addresses exist in both public networks (the Internet) and private ones (LANs) and since there are millions of them, it was decided to put them in specific classes to help organize the IP addressing structure and make it more easy to work with.

Today all IP addresses can be categorized into five different classes, each class having a specific range:

 IP Classes Default Subnet Mask Class A: 1.0.0.0 to 127.255.255.255 255.0.0.0 Class B: 128.0.0.0 to 191.255.255.255 255.255.0.0 Class C: 192.0.0.0 to 223.255.255.255 255.255.255.0 Class D: 224.0.0.0 to 239.255.255.255 Class E: 240.0.0.0 to 255.255.255.255

Out of the five classes, the first three, A, B and C are used on the Internet by its users in order to communicate, while the rest, D and E, are reserved for other reasons. In most cases, you will always be working with Classes A to C.

Each Class was also given a certain subnet mask, called the "default subnet mask." The default subnet mask allowed us to define the range each network would have depending on the class it belonged to.

You might have read or hear people saying that Class C networks can hold up to 255 IP addresses, while Class A networks hold a lot more. While this is correct, they are really referring to the default subnet mask each class has, that determines the amount of networks these classes hold.

By using a different subnet mask, other than the default, we are able to further split the networks into smaller ones to suit our needs.

Instead of continuing on the analysis of subnets, I'll refer you to my Web site (www.firewall.cx/) which covers the topic in the best possible way using easy to understand diagrams to help you "see" what happens during the break down.

If you find the information overwhelming, it might comfort you to know that it took me some time to fully understand it back in the days I was introduced to the topic!

This was last published in March 2007

## SearchUnifiedCommunications

• ### Microsoft's Nuance buy enriches call center, security products

Analysts expect Microsoft to integrate Nuance voice technology with a wide range of Microsoft products, including Teams and ...

• ### Microsoft update of Teams Rooms for Android falls short

Microsoft has yet to add to Teams Rooms on Android critical features available on the Windows version. Missing features include ...

• ### 5 steps to managing team collaboration apps

Team collaboration apps offer measurable productivity and cost benefits. Follow these five steps to address technical, security ...

## SearchMobileComputing

• ### How to deploy configuration profiles on iOS 14 and later

While mobile IT admins can deploy iOS configuration profiles manually or ask users to handle that task, they should learn how to ...

• ### Chip shortage leads to higher prices, wait times for PCs

A new Gartner report shows that PC shipments have increased, despite a semiconductor shortage caused by high demand, ...

• ### Chip shortage driving up PC prices, wait times

Businesses pay more for PCs and find it difficult to replace aging ones as the ongoing chip shortage leaves computer makers ...

## SearchDataCenter

• ### Programmable processor technology for next-gen data centers

The right processing technology can benefit your data center. Learn about advancements in CPU technologies, recent vendor ...

• ### Data processing units accelerate infrastructure performance

DPUs often run on networking packets to move information in the data center, instead of supporting processing workflows. Get an ...

• ### New Intel Ice Lake processors boost performance, security

Intel launches third-generation Xeon Scalable processors that bolster security, accelerate common data center workloads by 46% on...

## SearchITChannel

• ### Cloud consulting services attract investor dollars

A spate of deals involving Ensono, Ahead, Upstack and Syntax reflects growing confidence in cloud consulting firms; other IT ...

• ### IT industry's lack of diversity remains key issue in 2021

The first quarter of 2021 saw almost no changes in the composition of IT leadership teams. Here's how channel partners can change...

• ### How MSPs can build a post-merger integration team

Combining two companies is a complex undertaking, spanning employees, operations and line-of-business applications. An ...

Close