Basic overview of IPv4 Addressing
A quick look at the classes of IPv4 addresses and the limitations of each class. Understanding this helps us to understand why we subnet.
Note: I use Network ID below at a time which should be called Network Address. Technically Network ID is the information related to the network portion of the address, and Host ID the host. The Network Address is the first possible IP address in a network or subnet (sometimes referred to as the Subnet Address). Here's an example:
Network ID: 192.168.1
Host ID: 15
Network Address: 192.168.1.0
Sorry for any confusion.
In the above video, the classes for private IP addressing are mentioned. These three, plus two more, can help define a nice set of information one might see on the Network+ Certification. Here are the details of the five IPv4 addresses (in bold) I recommend memorizing and why they are helpful.
Here's a handy table, in case you just want the 5 IP addresses and what they are.
|10.___.___.___ /8||Class A Private|
|172.16-31.___.___ /16||Class B Private|
|192.168.0-255.___ /24||Class C Private|
With this information, it should be possible to answer most, if not all, IPv4 addressing related questions.
Before we get to the math, this is basically what subnetting is doing with a network address space.
Now that we understand the concept, it's time to calculate the specifics. Once we do this the hard way, we'll do it the easy way. (Note: the thumbnail image was taken in the middle of making changes. The Class A subnet mask does not match the binary. I hope this clears up any potential confusion.)
When trying to apply subnetting to a scenario, we need to ask some specific questions.
Now that the network specifications are known, we can calculate the subnet mask and CIDR.
Besides calculating the specific subnet mask and CIDR numbers, a subnet calculator can help with configuring the specifics of a network. These last three questions might be something you encounter when actually setting up a subnet in the enterprise environment.