Your public IP address is:
What is this public IP?
Public or external IP addresses are those addresses that are routed on the internet. It can be IPv4 or IPv6. And it is a unique address assigned by the internet service providers. And most internet users are connected behind a single public IP address except for some enterprise users who require multiple IP addresses for different services they offer. And mostly for home users, it is always a single public IP address, and many users can be connected behind a single public IP address.
But how can many users connect to the internet using a single public IP? The IP address should be unique right ?
That’s where private or local IP addresses can come to your rescue.
How do you tell if an IP address is public or private?
If you check the IP address at your home or even at the office from your machine by doing ipconfig or ifconfig you would most likely get an IP address from the private IP address range that is 10.0. 0.0/8, 172.16. 0.0/12, 192.168. 0.0/16 also known as RFC 1918 addresses. Those Private IP addresses cannot be routed across the internet. Instead what your router would do is convert those Private IP address to Public IP address with a feature called NAT. This means each user on the internet will have unique public IP addresses.
So If you are seeing an IP address in the RFC1918 range it is a private range and rest all are public IP addresses. There are some IP addresses between 224.0. 0.0 to 239.255. 255.255 those are called multicast addresses which is used for special network purposes and protocols.
One of the benfits of using the private IP address range is that, it provides flexibility when it comes to IP assignments. You could have the same private IP addresses used by the other users. For eg: You can have IP address 192.168.1.10/24 in your network and your neighbor next to your block can have the same subnet. however each users will have unique private IP addresses.
What happens if you try to route the private IP address to the internet?
Most of the ISP’s by default would block the RFC1918 addresses entering into their routing table, there were instances in the past that some part of the internet went down when some users started to advertise the private IP address to the internet. Currently, ISP’s are blocking them, so even if you advertise private range it would block at the ISP level.
Will my public IP change?
It depends on how your internet IP configuration has been set up by your internet service provider. Most of the household broadband networks use something called DHCP for IP assignment, hence you would see the public IP addresses keep changing. However, in an enterprise network, they use mostly the static public IP addresses so the public IP address may remain the same.
If you want to stop your IP address from changing, you can reach out to your local ISP and request static IP addresses. After you get the static IP addresses from the ISP, they would configure them for you. Afterward, your public IP would never change.
There would be some charges involved for getting those static IPs though.
Does IP address change with location?
You might also be wondering, every time when I move from one location to another my IP addresses are changing why is that. Since the public IP addresses are unique, each block of those public IP’s are assigned each geo locations by the Internet Assigned Numbers Authority (IANA). And these IP address are then again split as a separate subnets by the internet service providers.
Not only just the location, you can even switch between your mobile internet and the home broadband and you will notice your public IP address changes.
What is the purpose of IPv6?
When the IPv4 works perfectly fine what is the need of a IPv6 you might be wondering, as you may know when the internet was initially built no one has ever thought it would grow so big. As the internet has became huge, and the usage of the public IPv4 was increased over time. The exhaustion of IPv4 addresses also started and we started running out of public IPv4 addresses. That’s when the IPv6 was released.
Currently, the internet comprises of both IPv4 and IPv6 traffic, and moving out of IPv4 is still a challenging task for many internet users. Some enterprise users are still using only IPv4, and some are planning to migrate and using dual-stack meaning running both IPv4 and IPv6 on the environment. Eventually, we will move out of IPv4 and migrate to IPv6. And IPv4 will be the thing in the past!