What is IPv4? And why it matters to you?
You might have encountered this term IP address a few times, even if you don’t directly work with IT. When you move into an old student dormitory with ethernet sockets or need to work with an internet-capable device, your IT team will give you the following instructions.
“Open Settings, and set the IP address to 192.168.255.10.”
“If still no internet connection, type ‘ping 127.0.0.1.’ and screenshot the response.”
Have you ever wondered what the heck does that mean? Why those numbers? Well, now it is time to find it out.
In the past posts, we discussed two Internet architectural abstractions, the OSI and TCP/IP models. You can read OSI Model - The Standardization of Computer Networking and TCP/IP Model - How Internet Works in Reality. The IP address was often mentioned with the example of sending an email, and we will look closely at this protocol in this post.
What is IPv4? What is an IP address?
IPv4 means Internet Protocol version 4. It lives in layer 2, the Internet Layer in TCP/IP model. Read more about the TCP/IP model. Similarly, there is IPv6, which we will discuss in another post. An IP address is a logical address used to uniquely identify a device on an IP network. An IP address consists of the following chunks.
This 32-bit integer space provides over four billion addresses. However, it soon tends to run out. To solve the limitation, here are the two major ways to regroup the IPv4 addresses depending on the purpose. The exponential growth of internet users is the primary driving force regrouping IPv4 addresses. Let’s have a deeper look.
IPv4 addresses can be divided into five classes: A, B, C, D, and E. Class A, B, and C are relevant to most of us. It was made to ensure that organizations received address blocks appropriate for their network size without wasting address space.
IPv4 addresses can also be divided into private and public addresses. The purpose of public IP addresses is to provide unique and routable addresses for devices to communicate across the global internet. On the other hand, private IP addresses enable internal communication within a private network and help conserve the limited pool of available public IP addresses by allowing multiple devices to share a single public IP address. Here is a table showing the IP address ranges within different classes.
| Class | IP Address Range | Number of Addresses |
|---|---|---|
| A | 10.0.0.0 – 10.255.255.255 | 16,777,216 IP Addresses Per Network ID |
| B | 172.16.0.0 – 172.31.255.255 | 65,534 IP Addresses Per Network ID |
| C | 192.168.0.0 – 192.168.255.255 | 254 IP Addresses Per Network ID |
Example
Look back to the example mentioned at the beginning of the article; it starts to make sense.
“…set the IP address to 192.168.255.10…” means we are now configuring the device in the local network, e.g., your company intranet. As it lives in the class C private address range, it roughly says that this device can directly communicate to a maximum of 250-ish devices without leaving the local network. And all other devices in this local network can quickly locate and send packets to this device. If one device is retired, a new one can reuse the same local IP address and replace the old one without much configuration effort from IT.