Private vs Public IP Addresses: A Complete Beginner Guide

When it comes to the private vs public IP discussion, it is clear that internet users often focus on their public IPs. However, did you know that private IPs exist as well?

Every device connected to the web has an Internet Protocol address or IP address, and both private and public IPs are equally as important.

In this article, we discuss what private and public IP addresses are. Furthermore, we compare the two to help you understand how they both work and what the main differences are. We also note how private or public IP addresses relate to Internet security. 

What is a private IP address?

A private IP address, also known as an internal or local IP address, is used in your private network, otherwise known as an internal network. To connect to the internet, you probably use a router, and your devices connect to it via cables or Wi-Fi. 

The router needs to communicate with every device, and it assigns a private IP address to each of them. This address is only visible inside your network, which means it cannot be found on the internet.

Imagine using a wireless printer to print a document. To do it, you need to send a request via your PC or mobile device using your private network. The printer probably has a private IP address of its own, and it will receive the request to start printing. However, if someone outside your network attempts to do the same, they will not succeed.

Your private IP addresses are also there to help you with how your router directs online traffic. Suppose you are researching something online. When you are using your mobile device to do that, the router also needs to read your device’s private IP to know where to send search results. It knows that you are using a mobile device rather than a PC, thanks to its unique private IP address.

As every device has a private IP address, you probably have several of them, as two devices connected to the same router cannot have the same address.

How is your private IP determined?

Private IP addresses look the same as public IP addresses. IPv4 addresses are numeric strings with full stops in between the digits, and IPv6 addresses are alphanumeric strings with colons in between. 

Network routers are also assigned private IP addresses, and they use them to direct internet traffic internally. The unique thing about routers is that they have default IP addresses, which are assigned depending on your router’s manufacturer. 

While most routers, including Linksys, use 192.168.1.1 as the default IP address, that is not true for every manufacturer and router model. NETGEAR and D-Link use 192.168.0.1, while SMC and Belkin use 192.168.2.1. Cisco uses several private addresses, including 192.168.10.2 and 192.168.1.254. You might know these IPs as 192 IP addresses. 

What is LAN?

LAN stands for Local Area Network. It is a network of computers within the same space, such as a residential area, a university building, or an office space.   

So far, we have discussed private addresses for individual users. As an individual user, when you start using services from your internet service provider (ISP), a technician comes and sets up a local network for you so that you would have an internet connection. Afterward, you can connect your PC, laptop, mobile phone, and smart home devices, such as your TV or printer.

However, private networks can be much larger than that. Imagine a company with multiple devices that need to communicate with each other. All devices with unique internal IP addresses connect to the internet via LAN, and nobody outside the network can access it.

What is a public IP address?

Think of your public IP as your home address. A public IP address visible on the internet is analogous to a street name and a building number that determine where you reside. A public IP address is how your router communicates with the World Wide Web. 

Also known as an external IP address, your public IP is the address that your Internet service provider assigned to you. It is a unique string of numbers you need to go online. Once online, your router uses private IP addresses to direct the internet traffic it receives further.

You can search “what is my IP address” using a search engine to find your public IP address. The sources providing the results can also reveal your ISP, country, and even city.

Of course, personal details remain anonymous, and, therefore, it is safe to say that your IP address is not exactly like your home address. That said, your external IP is more visible if we compare it to a private IP address.   

Differences between public and private IP addresses

Public and private IP addresses essentially serve the same purpose. Yet, they are very different in terms of who has access to them. Here is a short overview of the main differences between these two types of addresses:

• A private IP address is used in a private or LAN network, while a public IP address is used in a public network (internet)
• A private IP cannot be recognized on the internet, whereas a public IP is visible online
• A private IP is only unique on the home network, but a public IP is unique globally
• A private IP is free, while there are usually costs associated with a public IP address
• A network administrator assigns private IP addresses, whereas an ISP assigns public IPs

Overall, you need both a public and a private IP address if you want to access the internet. They work hand in hand to make the entire experience possible and are both equally as important. 

Public IP ranges vs. private IP ranges

The Internet Assigned Numbers Authority (IANA) has reserved certain ranges of IPv4 addresses for private use. Millions of private networks around the globe use reserved IP addresses within these ranges. Three classes exist:

• Class A: 10.0.0.0–10.255.255.255 
• Class B: 172.16.0.0–172.31.255.255
• Class C: 192.168.0.0–192.168.255.255

As you can see, these IP address ranges are not wide. However, because we can reuse private IP address ranges in local networks, they do not really need to be wide, as local networks all work independently from each other.

Since public IP addresses need to be unique, public address ranges are much wider than private address ranges. In fact, they include all the numbers that are not reserved for the private IP ranges.

The three classes shown above are reserved for local networks, but IANA has the IPv4 Special-Purpose Address Registry that shows how other IP addresses are reserved for other purposes, such as documentation.

Ultimately, every combination of numbers that are not reserved can be your public IP address, as assigned by your ISP. 

Why use private IP addresses

Even without realizing it, you are probably already using a private IP address assigned to your device by your router. The question is, how do we use private IP addresses? 

Every device within your home network has a unique private IP, which helps the router provide instructions or redirect the traffic from the Internet to the correct device. Moreover, it helps your devices communicate with each other over the local network. As you can see, a private IP address is an inseparable part of every network that uses a router. 

How to check if you are using a private or public IP address

When you are doing anything online, you are technically using both public and private IP addresses. As we discussed already, to check your public address, you can type “what is my IP address” into your search engine, and you will learn your public IP address instantly.

To check private IP addresses, you need to access network properties via your device. Here is how to find your private IP address on Windows 10.

1. Go to Settings and click Network and Internet.

2. Select Status on the left and click Properties.

3. Scroll down to Properties to find your private IP address on the right of the IPv4 address.

It is just as easy to find your private IP address on Mac, iOS, and Android devices.  

This example demonstrates how to find the IPv4 address, but remember that IPv6 addresses exist too. If you wish to learn more, we have discussed in great detail the differences between IPv4 and IPv6 in a comprehensive guide. Although the latter should have replaced the former, IPv6 adoption issues continue to plague the global internet. 

Hiding your IP address

There is no need to hide your local IP address. It remains private and visible only to the devices that are part of the same network. However, hiding your public IP is always a good idea, as your ISP can trace your online whereabouts as soon as you establish an internet connection. 

Unfortunately, you are more vulnerable to various cyberattacks and other scams when you are using your public IP, which is why you may choose to hide it.

If you want your public IP address hidden, you can use a VPN (Virtual Private Network) or a proxy server. Even though they both offer a higher level of privacy and security, there are several key differences between the two. 

Conclusion

To sum up, private IP addresses are part of every local network, and there is one such network in almost every home or office. All the devices connected to the same router have a private IP. 

Private IP addresses are not visible on the web like public addresses, and their main purpose is to help routers communicate with devices in the home network and, in turn, help the devices themselves communicate with each other.

Whenever you connect to the web, you also get a public IP address, which is visible online and serves as your unique online numeric code that makes communication between servers on the public internet possible. Overall, both private and public IPs are indispensable in today’s world.