What is subnetting

If we picture that in binary, it looks like: The number of host bits available for tweaking is equal to one.

What is subnetting

The important thing to remember when creating a subnet mask is that we must have a series of all ones followed by a series of all zeros.

What is subnetting

Because of this fact, all subnet masks will have limited values. In fact, we can only have the following values within an octet of a subnet mask: To get this numbers we simply convert each binary number into a decimal number.

Remember that the subnet mask must have ones on the left hand portion, so the possible numbers in one octet are: The number of subnets is 2 number of ones which we used to subnet our network.

Splitting Up Addresses

For example, in case a this is 20, which is 1 subnet. In case b this is 21, which is 2. In case c this is 22, which is 4. In case c this is 23, which is 8 subnets.

In case d this is 24, which is 16 subnets, and so on. When it comes to the number of hosts per subnet, the number is 2 number of zeros In case a this iswhich is In case b this iswhich is In case c this iswhich is In case d this iswhich is 30, and so on.

We subtract 2 because we have to reserve the network address and the broadcast address in every subnet. The first address in a subnet is the network subnet address. The last address in every address is a broadcast address. We also have to know the address of every subnet.

To get that we have to know the step which we have to take to get to the next subnet. To determine the step to get to the next subnet, use the formula 2 number of zeros in changing octet.

So now that we know all those numbers, we can subnet our network more precisely.

What is subnetting

When subneting, we pay attention to the octet in which the change occurs. We have the following IP address and a subnet mask: How many hosts per subet will we have?

Write the network and broadcast address for every subnet. Write the first and last address that we can use for hosts on a subnet. Write subnets in short notation.

The decimal notation for that subnet mask is We use this mask for all our new subnets.IP Subnetting Made Easy [John J Kowalski] on benjaminpohle.com *FREE* shipping on qualifying offers. I originally developed this book for my networking students at the community college where I teach and it is at their urging I have decided to publish this book.

Since then. Subnetting and Tables Subnetting is the concept of dividing the network into smaller portions called subnets. This is done by borrowing bits from the host portion of the IP address, enabling more efficient use of the network address.


Use the Subnetting Cheat Sheet to Answer Any Subnetting Question You Get! My Cisco CCNA training students laugh when I tell them I am going to show them how they can answer any subnetting question in 15 seconds flat. Subnetting Questions with Detailed Answers: These questions were designed to test your knowledge of subnetting.

Hopefully, by the end of the worksheet, the exercise will make you feel more comfortable with your ability to subnet ip addresses. Subnetting a Class B network can involve some serious thought! As a network administrator, you'll have to know it and know it well.

Todd Lammle walks you through clear instructions and simple. How to Calculate Subnets Subnets and Hosts Borrow 2 bits S S H H H H H H # of subnets = 2 2 = 4 Subnet mask = 2 bits = + 64 = Range of hosts = 2 6 = 64 TT Range Useable Range Network ID 0 – 63 64 – 65 - – - Broadcast – Address.

Networking Understanding Subnets and CIDR