• Welcome back! In this installment, we’re going to examine VLSM (Variable-Length Subnet Masking, RFC 1878), and how to use the subnetting shortcuts to solve VLSM problems. I’m sure that it won’t surprise you to know that we’ll need the powers of two chart: n = 8 7 6 5 4 3 2 1 2n = …   Read More

  • In this, our final look at subnetting for now, we’ll examine more “find the subnet” problems, specifically those in which the subnet/host boundary lies within the second or third octets. Here is the powers of...

  • In the previous editions of “Subnetting Shortcuts”, we solved various types of problems involving subnet masks. This time, we’ll look at some more complex cases, specifically those in which the subnet/host boundary lies within the second or third octets. But first, because our lives would be incomplete without it, here is the powers of two …   Read More

  • This time, we’ll use the shortcuts to solve some different types of problem. Instead of “find the mask”, this time the challenge is to “find the subnet”. Ready? Here’s the first problem: given a host address of 192.168.1.100 and a subnet mask of “/27”, determine the host’s subnet, the legal range of host addresses on …   Read More

  • In “Part 3”, we solved a subnet masking problem using shortcuts. This time, we’ll use the shortcuts to solve some additional problems. Here’s the first problem: given an address space of 172.16.1.0/24, divide the network...

  • VLANs, as we discussed before, are used to create logical broadcast domains on switches. However this information needs to be synchronized between switches. Manual configuration can be tedious in a large scale network, so understanding...

  • In “Part 2”, we solved a subnet masking problem using binary. This time, we’ll look at some helpful shortcuts that can make solving such problems faster and easier for most people (and less error-prone, as...

  • Virtual LANs (VLANs) seem to be one of the easiest topics to configure in the CCNA course. However, there can be some tricky things that are often overlooked. First, you must create your VLANs, then...

  • In Subnetting Shortcuts- Part One, we reviewed the classful addressing scheme, and the purpose of a subnet mask.  Now let’s look at an example. Let’s say that you’ve been given an address space of 192.168.1.0/24,...

  • Many CCNA candidates have trouble with subnet masking (and some CCNP candidates, as well!). Over the next few weeks, we’ll learn some shortcuts that make subnet masking calculations easier. But first, a review … Recall...