What Is a Public IP Address and How to Check If You Have One

What an IP address is and how a public one differs from a private one

An IP address is a device’s number on a network, much like the postal address of a house: it is how data finds its recipient. Addresses come in two kinds. A public address is unique across the whole internet and belongs to one subscriber, so anyone in the world can reach it directly. A private address works only inside a local network: the same private address is used by millions of devices in different homes at once, and it can’t be reached from the internet.

At home you almost certainly have both kinds. Your phone, computer and TV get private addresses from the router, usually like 192.168.0.x or 192.168.1.x. The router itself reaches the internet through a single external address that your provider gave it. It is called the WAN IP, and it is this address that is either public or not.

While you are just browsing, you can’t tell the difference: the router swaps your private address for its external one, and the replies come back to you. But if someone outside wants to connect to you first, like a friend to your Minecraft server, they can only address the external one. With a public address the request reaches your router, and there it can be passed on to the right computer (this is called port forwarding). With a private one, the request never arrives.

Why your provider may have no public addresses for you

There are only about four billion IPv4 addresses, and far more devices than that on the network. The free ones ran out long ago, so many providers economize: dozens or hundreds of subscribers go online through one shared public address, while each of them has a private address on the router. This scheme is called CGNAT (Carrier-Grade NAT, address translation on the provider’s side).

In everyday life you won’t notice: sites open and videos load. But you can’t accept an incoming connection. The request arrives at the shared address, and the provider’s equipment doesn’t know which of the hundreds of subscribers to pass it to, so it simply drops it. A server on your home computer stays unreachable in this case, however you configure your own router.

How to tell a private address from a public one

An address is private if it belongs to one of the ranges reserved for internal networks. They are easy to remember:

• 10.0.0.0–10.255.255.255 (addresses like 10.x.x.x): private networks, often used by providers and offices.
• 172.16.0.0–172.31.255.255 (from 172.16.x.x to 172.31.x.x): private networks.
• 192.168.0.0–192.168.255.255 (192.168.x.x): the most common range on home routers.
• 100.64.0.0–100.127.255.255 (from 100.64.x.x to 100.127.x.x): a range set aside specifically for CGNAT. If your router got an address like this, your provider certainly shares one address between many subscribers.

Any other address, apart from a few special ones such as 127.x.x.x and 169.254.x.x, is public. Still, a public address on the router is not yet a guarantee, so first compare it with what the internet sees (the steps are below).

How to check whether you have a public IP

1. 1Open your router’s settings. This is usually 192.168.0.1 or 192.168.1.1 in a browser, and the login and password are often printed on a sticker on the case.
2. 2Find the internet connection status: the section is called “Status”, “WAN” or “Internet”, depending on the model. It shows the IP address your provider gave to your router.
3. 3Find out which address the internet sees. To do this, type “my IP” into a search engine or open any website that shows your external address. Turn off any VPN or proxy first, otherwise you will see the address of its server.
4. 4Compare the two addresses. If they match and the address is not in the private ranges above, you have a public IP.
5. 5If the address in the router is from a private range, or the two addresses differ, your IP is not public: there is one more NAT of your provider between you and the internet.

Can’t get into the router, for example because it belongs to the provider and is locked with a password? Then open a command prompt and run tracert 8.8.8.8 on Windows or traceroute 8.8.8.8 on macOS and Linux. The first line is your router. If the second or third line shows an address from 100.64.0.0–100.127.255.255, you are behind CGNAT. If there is no such address, that doesn’t prove you have a public IP: it is simpler to call your provider and ask.

Static and dynamic public IP

Even a public address can change. A dynamic address is changed by the provider, for example when the router restarts or every few days. A static one is assigned to you permanently, usually for an extra fee.

This matters for a home server: if the address changes, your friends can’t connect until you send them the new one. There are two ways around this: order a static address from your provider, or set up a dynamic DNS (DDNS) service. It ties a permanent domain name to your changing address, so your friends only need to know that name.

What to do if you don’t have a public IP

A private address is not a dead end: there are several ways to manage without a public one.

• Order a public IP from your provider. This is usually a paid service, connected on request or by calling support. Make sure the address will be public and reachable from the internet, not just permanent inside the provider’s network.
• Build a virtual network. Programs such as Radmin VPN or ZeroTier join computers into one “local network over the internet”: your friends join your network and connect to the server at its address. You don’t have to configure the router or have a public IP, but every player has to install the program.
• Use a tunnel service. For example, playit.gg gives you a public address and forwards connections to your computer. Your friends don’t have to install anything, but the server then depends on a third-party service.
• Don’t keep the server at home. Paid hosting and free hosting in the browser work without a public IP of your own and without router setup: the address is public on the host’s side.

A public IP and security

When your address is public and a port is open, anyone can try to connect to you, not only your friends. Don’t post your IP in open chats and forums, open only the port you need on the router, and keep Java and the server itself up to date. For a private game, turn on the whitelist: the command /whitelist on enables it, and /whitelist add with a player’s name adds a friend. The full list of protective measures is in the article How to Secure a Minecraft Server and Your Home Network: A Security Checklist.

Frequently asked questions

Are a public IP and a static IP the same thing?

No, these are different things. “Public” means the address is reachable from the internet. “Static” means it never changes. There are public dynamic addresses (reachable from outside, but they change) and private static ones (they never change, but can’t be reached from outside).

Do I need a public IP to play on someone else’s server?

No. When you connect to another server, the connection is outgoing, and a private address is enough. A public IP is needed only by whoever accepts connections at home: runs a server, a camera or remote access.

Does a public IP affect speed and ping?

No. It doesn’t speed up your internet or reduce delay; it only decides whether people can connect to you from outside. Speed and ping depend on your plan, the quality of the line and the distance to the other player.

What next

If you have a public IP, go back to the guide How to Make a Minecraft Server to Play with Friends: the next step there is installing the server. How to open the port on the router and in the Windows firewall, and then check it, is described in the article How to Open Port 25565 for a Minecraft Server and Find Where It Is Closed. If you don’t have a public IP, use the second or third method from the guide to making a server: they don’t need one.