Difference Between Public and Private IP Addresses and What They Mean
As we mentioned in the first blog of our “What is an IP Address” mini-series, “An Internet Protocol Address, or IP address for short, is like your computer’s phone number. Without it, your computer wouldn’t be able to connect to the Internet. Every computer, tablet, smartphone, and Internet-enabled device has its own IP address.”
But there is not just one type of IP address. In fact, there are many different types of IP addresses. In our blog today, we will go over the difference between public and private IP addresses, as well as how they work together.
Public
A public IP address is a unique set of characters used to access the Internet. They are given to users via the Internet Service Providers (ISPs) and are typically assigned to a router.
Public IP addresses have various functions. For example, they make sure that online content, like websites, are accessible. They also ensure messages are delivered to your email server successfully. To put it simply, they act like portals to the Internet.
Most importantly, public IPs allow users access to their machines remotely. So long as the public IP address is known, users can install and configure services, such as VPN, on their server. This is done by utilizing their Public IP address provided to them by their ISP/Provider.
Private
You might instinctively want to compare public and private IP addresses like apples to oranges. After all, they are antonyms of each other. But in reality, they work in a partnership.
Public IP addresses are provided by the ISP, but private IPs are designated by the router to a specific device on the local network. Where public IPs are completely unique and exclusive to one network, private IPs are used by devices inside the local networks sharing an address from a smaller range. Because Private IP addresses, or sometimes known as internal IP addresses, aren’t routed on the Internet, they need public IPs in order to access the Internet.
Therefore, the traffic is exchanged between public and private IPs, but exclusive to your own private network. This allows your computer to communicate to your other computer or devices without leaving the private network.
In between the two is your router that keeps your private network secure. It is important to note that if your router gets compromised, your whole network is at risk as well. Although computers have firewalls, devices such as cameras and printers typically do not.
How Do They Work?
With a normal broadband or fiber line in a simplified network, there is a one-to-one relationship between the public IP address and the private IP network being accessed. The router typically utilizes Dynamic Host Configuration Protocol (DHCP) to assign internal IP addresses. However, that public IP refers to you, the user.
For example, your neighbor across the street will have a different public IP address from you. Because there is a 1:1 relationship with the IP addresses. You could actually make a request just to that IP address and access the resource.
To better help visualize the relationship between public and private IP addresses, take a look at the diagram below:
Where it says “Home Network” is basically the private network that the devices are communicating to each other. The devices can access the Internet through the router.
No-IP Solutions
Most networks have Dynamic DNS before finding a solution. A dynamic IP address is one that changes from time to time, and isn’t always the same. If you have a residential cable or DSL service, you most likely have a dynamic IP address. Most of the time, routers have dynamic DNS or DDNS built into the router.
The issue is that if you don’t know what the new IP is, then you will not be able to find where your network is to access it. Dynamic DNS makes a dynamic IP address act as though it’s static, even though it’s not. With No-IP, a user will create a hostname (that is typed into the browser or application) to connect to a device remotely. When the IP address changes at the network location, the Dynamic Update Client (DUC) will update No-IP’s servers, so the remote connection is never lost.
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