Networking 103 IPv4 Addresses and Subnetting

In this Learning Lab you will learn a lot about IPv4 addresses, binary numbers and subnetting


Completion Time: 45 minutes

  • Learn about IPv4 addresses
  • Understand how to use binary numbers
  • Learning about subnets, hosts and how to do subnetting


  • You have some general knowledge about networks and/or have completed the labs: Networking 101 and 102.
  • Our focus in this lesson will be on wired networks which for our purposes is what you need to learn. Wireless networks have other network components not covered here.
  • The discussion is based upon IPv4 protocol; otherwise known as Internet Protocol version 4.

Additional Information

Step 1. IPv4 Addresses

Why Should I care about IP Addresses?

Every device on a network has a unique IP address. This IP address along with a MAC address is used to access and communicate with all network devices. Without IP addresses there would be no Internet and without the Internet you wouldn't get to play Internet games all day! There'd be no surfing the Internet, so finding answers and learning new things would be relegated to only books and your instructor. Yuck!

What are IPv4 Addresses?

IPv4 stands for Internet Protocol version 4 and is a core protocol used for Internet communication. IPv4 was introduced in 1983, and despite the introduction of IPv6 continues to route most of the Internet traffic today. For more information see IPv4.

An IPv4 address is composed of four octals. Each decimal value is separated by a dot so it's sometimes referred to as dotted decimal notation. Each octal is made up of eight bits, and each bit can be a value of 1 or 0.

IPv4 Address

Taking a closer look at the IP address above in the table each value is shown to be represented by eight bits with each bit represented by a 1 or 0. Don't worry about the bits right now, but note that there are always eight of them for each octal, and that there's always four octals in an IPv4 address.

IPv4 Address

Here's another IPv4 address. The format is the same as it will always be and there are 8 bits that represent each octal which will always be the case. Another important tidbit is that 8 bits make up what is called a byte which is what we called an octal. Since an IP address will always have 4 octals aka bytes, that means that an IP address is always 4 bytes long or 32 bits ( 8 bits times 4 = 32 bits)

Quiz. Scroll Down for Answers

  1. How many octals are there in an IP address?
  2. How many bits are in an octal?
  3. What are the possible values of a bit?
  4. Can you name at least three network devices that you use either directly or indirectly?


  1. 4
  2. 8
  3. 1 and 0
  4. laptop, mobile phone, headset

Next Step: Learn about Binary Numbers