Subnetting is a very interesting and important topic. It's most possible that most of you have heard about it or have some idea what it's all about. For those who haven't dealt with subnets before... hang in there because you're not alone! Keep in mind we also have our website's forums where you can post questions or read up on other people's questions and answers. It's an excellent source of information and we highly recommend them!

For some reason a lot of people consider Subnetting to be a difficult subject, which is true to some extent and especially for people who are new to the networking world.  Readers will be interested in knowing that mastering Subnetting is not all that difficult - it simply requires time, practice and a lot of patience.

A world of advice

If you started reading the IP protocol on this site from the begining and have understood everything, then you won't have any problem understanding subnetting... however if on the other hand readers feel like that could use a refreshing on their networking basics, we would highly advise visiting the IP Protocol section under Protocols to help them revise the necessary theory which is the foundation of Subnetting.

Subnetting on Firewall.cx is broken into 5 sections. Each section tackles a specific area and also provides the basic understanding for the next topic. Logically, as you move on to higher sections, the concepts and complexity will increase.

• Section 1: Basic Subnetting Concepts. This section is to help you understand what a subnet really is. Introduction to the Default Subnet masks is covered at first and then you get to see and learn how the network is affected by changing the subnet mask.

• Section 2: Subnet Masks and Their Effect. Here we will look at the Default Subnet mask in a bit more detail and introduce a few new concepts. Classless and Classful IP Addresses are covered here and you get to learn how the subnet mask affects them.

• Section 3: The Subnet Mask Bits. Detailed analysis of subnet mask bits. Learn to recognise the number of bits in a subnet mask, followed by an introduction to complex subnets.

• Section 4: Routing and Communications between Subnets. Understand how routers deal with subnets, how computers which are in different subnets can communicate with each other, along with a few general notes on subnetting that you should know.

• Section 5: Subnetting Guidelines. Some last information to help you plan your new networks and a few things to keep in mind so you can avoid future problems with subnets.