Hello everyone, in this Article we're going to be talking about the difference between public and private IP addresses, and to be specific I'm going to be talking about IP version 4 addresses.
So the first thing we have to know is what is an IP address?
Well, an IP address is a numeric address. It's an identifier for a computer or
device on a network. Every device has to have an IP address for communication purposes. And there are two different types of IP addresses: there's public and private.
So what are the differences between the two? So let's first talk about public IP addresses. Now when you order internet service from an internet service provider, they are going to assign your modem or your router in your home or business a public IP address. This public IP address is registered on the internet, it's what gives you access to the world wide web.
So if you don't have a public IP, you cannot access the internet. Public IP addresses are also unique, there are no duplicates anywhere in the world of public IP addresses.
Now when IP addresses were created, engineers didn't realize how big the internet would become because even though there were over 4 billion IP version 4 addresses available, the engineers thought that this would be enough. But they were obviously wrong because of the explosive growth of the internet.
So in order to prevent a shortage of public IPv4 addresses, engineers developed private IP addresses. Now private IP addresses are not publicly registered on the internet. So you can't access the internet using a private IP address. However if your device does have a private IP address and you want to access the internet, your private IP has to be converted into a public IP address before you can access the internet.
And this is because private IP addresses are only used internally such as inside a home or business. They are not used on the public internet. And a service that's inside your router called DHCP is what assigns your internal devices a private IP.
So as an example most homes and businesses are not going to have just one device that needs access to the internet, chances are they're going to have multiple devices that need internet access.
So all of those devices need a public IP address if they want to access the internet. Now you could contact your ISP and ask them for these additional IP addresses for all of your devices. But that's going to be more expensive, unnecessary, and more importantly, it'll be a waste of public IP addresses. And let's face it, if every device in the world had its own public IP address, we would have run out of public IP addresses already.
So what we can do instead is we can have the router assign the devices inside our home or business private IP addresses and when these devices need to access the internet their private IP address will be translated to the one public IP address that we have been given. And the service that translates this is called NAT or network address translation and it's a service that's built into our router.
So not only does it translate private to public but it also translates public to private. Because if a computer on the internet wants to communicate with a computer on this private network, the public IP address needs to be translated by
NAT to the private IP address for that computer.
Now private IP addresses have three different classes and these classes have different ranges. So a class A private IP starts with the number 10. This class is typically used for large organizations. Class B starts with 172, this is typically used in medium-sized organizations. And class C will start with 192. This is used in small organizations or homes.
Class C is the most popular range of private IP addresses that are used. So don't be surprised if you happen to check your IP addresses on your devices in your home if you see them starting with 192.168, because like I said it's the class that's mostly used.
Now if you want to find out what your IP address is this is how you do it. If you're using a Windows computer you just open up a command prompt and type ipconfig. On Mac and Linux computers, you just open up a terminal and type ipconfig. So here is the IP address for this computer and as you can see this is a class C private IP address that has been given to us by our router.
So since this computer is assigned a private IP, it's not going to show our public IP. But if you want to know what your public IP address is, you just open up a web browser, and then you will go to a website like whatsmyipaddress.com and that
web page will show you your public IP address. So to summarize, public IP addresses are unique while private IP addresses are non-unique because the same private IP addresses can be used in other private networks. Public IPs are publicly registered so they are able to access the internet, while private IPs are not publicly registered, so they cannot access the internet directly.
Public IPs are used externally on the internet while private IPs are used internally on local networks. Public IPs are assigned by your internet service provider, while private IPs are assigned by your router. Public IPs are not free, you have to pay for them. But private IPs are free. And as far as security, public IPs are not secure because they are used externally out on the internet, so they are traceable. So in order to make a public IP more secure you have to add security measures such as using a proxy or VPN, which hides
your public IP address. But private IP addresses are more secure because they are hidden from the internet. They cannot be traced outside of their own network because they are used internally.
Now even though private IPs are used internally, they still have to be translated to a public IP when you want to go on the internet. Which means your public IP is exposed on the internet.
