How many classes of IP address are there?


At some point, we have all heard of the IP address. Any device connected to the Internet has an assigned IP. Its purpose is to identify that device on the network so that it can communicate with other devices. But there are different kinds of IP. There is one IP for your device on your local home network and another for when you access the Internet. And the latter changes every time you restart your router.

IP is the acronym for  Internet Protocol or Internet Protocol. Together with the TCP protocol ( Transmission Control Protocol  ), they make possible communications between devices that, in turn, make up the network of networks that is the Internet. Both protocols were created in the 70s of the last century by Vinton Cerf and Robert Kahn, fathers of the Internet. It was first called ARPANET, a network for military use that later led to scientific use and, later, led to the Internet that we know.

For our day-to-day, any device that we connect to the Internet uses an IP address that differentiates it from the rest of the device. On the one hand, the private IP, within your home network. On the other, the public IP, allows you to access the Internet. Let’s look at the differences between the various IP classes.

Private or public IP address?

An IP address is a combination of numbers separated by periods. Among the IP classes, the private IP is the one that identifies each device or device that connects to your router. The router itself has its own private IP, From there, each new device connected to the router will change the final figure, which is assigned in order of connection. This address does not usually change and identifies the devices within your home network. Thus,  they can communicate with each other even if they do not access the Internet. In addition to public IP, we can also call it local or internal IP.

With the private IP, we can control, from the router, the use that these devices make of the network. For example, we can block them, temporarily or permanently, or we can do the opposite, prioritize that they have priority access to bandwidth. If you are a Movistar customer, you can control these parameters through the  Smart WiFi app and the  Alejandra Portal. So you don’t need to connect directly to the router.

But the IP address we are interested in is the public IP. It is the one that identifies your phone, computer, television, or video game console when it connects to the Internet. Some people use the simile of car license plates or identity documents. In part, they are similar, but as we will see later, it is not so at all.

When you connect a device to the Internet, your  ISP or Internet service provider assigns it a public IP address through the router using the DHCP protocol, an acronym for  Dynamic Host Configuration Protocol or Dynamic Host Configuration Protocol. Thanks to the IP, your device can communicate with other devices on the network, something necessary to check email, send WhatsApp messages, watch movies on Netflix or Movistar Plus+, or a million other things.

Practical example. If you check the speed of your connection with the Netflix speed test, you will obtain useful data such as upload and download speed, latency, or your public IP. The private IP is only known by your router. The public IP can be known as it is the identifier of your device. What’s more, through that IP you can know where a device is connecting from. Not the physical address but the town.

Fixed or dynamic IP?

A characteristic of the public IP address is that it is usually dynamic. In other words, each time a device accesses the Internet, it receives a different address that expires after some time. Thus, the IP addresses available for each Internet provider are used and reused, reducing the number of inactive addresses.

Another practical advantage for the user is that if you have a problem with a service or web page or the IP you are using is blocked for various reasons, by restarting your router you will receive a new IP to continue using said service. Fast and easy. And for Internet providers, it is an advantage to have dynamic addresses because it allows them to manage fewer addresses on their network.

Among the available IP classes, it is common to use dynamic IP addresses, but it is also possible to have a fixed or static IP address. This implies that a single IP identifies the same device in a fixed way. Fixed IP addresses are used for specific services such as servers. The machines that host files, online services, or web pages have their own IP to facilitate their identification. And they are usually paid. That is, you can request a fixed IP  but this will have an additional cost, unlike the dynamic IP.

Among the advantages of fixed IP addresses, they offer faster and more stable connections, hence their use for private networks or for hosting web pages. On the other hand, being a fixed address, it can be a victim of external attacks that prevent it from working properly, such as the popular  DDoS attacks that saturate servers until they fall off the network.

For the rest, the use of dynamic addresses has another advantage, such as taking advantage of available addresses. Precisely, one of the problems of the Internet in recent years is that the available public IP addresses are running out. Hence, little by little, Internet providers are migrating the version of the current IP protocol, IPv4, to the IPv6 version, which offers a  greater range of available addresses.