A properly designed subnet can do wonders for the security and performance of a network. The main idea in subnetting is to divide a network into smaller pieces, which we call subnets. Actually implementing a subnet is typically more difficult than simply using the default subnet mask of 255.255.255.0. This usually means that temporary or smaller networks do not need to be subnetted.
Security sees benefit since the IP addresses of the host computers on each subnet are masked by the network address- which means they are invisible to the outside world. We call this network address translation, or NAT. This same technique helps conserve IP addresses, since all hosts on the subnet essentially just use the network IP address during communication.
First, Some Basic Review: If you’re a little rusty on the basics of subnetting, don’t worry. We’ll cover everything you need to know from beginning to end. First thing first: we need to learn about the IP basics.
The current version of internet protocol, or IP, is IP version 4. This IP version allows four octets of data to represent an IP address. Each octet is considered to be a byte, so there are 8 bits in every octet. Note that in binary form you can see that there are 8 numbers, each one consisting of a bit. Finally, each octet is separated by a period, as shown below.
Each IP address is usually represented in decimal form, as seen above as “192.168.2.1”. However, each IP address is actually used by computers in binary form. You may have noticed a huge flaw in IP version 4: the amount of unique IP addresses is limited! To be exact, only 4,294,967,296 unique IP addresses can be created. This may seem like a large number but keep in mind every single device in the world needs a unique IP address to communicate with one another while online.
The IP version 6 protocol was created for when the transition is needed. Most computers don’t use IPv6 just yet, but in the future it will inevitably be used. (In case you were wondering, IPv6 will support 2^128 unique IP addresses… egad!)