Static IP vs. Dynamic IP: How Are They Different?

Which one should you pick, a fixed IP or one that keeps changing?

Static IP vs. Dynamic IP: How Are They Different?

Dynamic IP addresses are assigned automatically and can change when you restart your computer. Static IP addresses require manual setup but stay the same even after restarts. Is one option better than the other?

What Is an IP Address?

An IP address is like a unique number that tells computers where to send information on a network. Imagine it's like mailing letters to different houses with their own addresses.

The most common way computers talk to each other on a network is through something called TCP/IP. It's like the language they use to understand each other.

Every computer on a network has its own special IP address, just like each house has a unique address. This address helps make sure that the information goes to the right place.

When two computers want to share information, they break it into little pieces, sort of like sending a long message in small parts. These little pieces are called "packets." Each packet gets a label with some details, like how big it is, how many pieces there are, and where it fits in the message.

Then, these packets take turns going back and forth between the two computers in their conversation until they've shared all the information they wanted to. It's kind of like talking on a walkie-talkie, where you say a bit, and then the other person talks back, and this goes on until the conversation is done.

This helps the information to be put back together when it's received and also helps figure out if some parts are missing.

Each part of the information must have the destination device's address so that the network equipment knows where to send them. The sender's address is also added so that the receiving device knows who to respond to or ask to send the missing parts again.

IPv4 and IPv6: What You Need to Know

There are two types of IP standards in use: IPv4 and IPv6.

IPv4 is the older and more common standard. It uses a 32-bit address format, which is made up of four numbers, each ranging from 0 to 255. IPv4 addresses look like this:

192.168.1.24

IPv6 is the newer standard, designed to solve the problem of running out of IPv4 addresses. It provides a much larger pool of available addresses by using a different format.

An IPv6 address is like a special code with 8 parts, and each part has 16 slots for numbers. These numbers can go from 0 to 65535. So, a complete IPv6 address looks something like this:

fe80:0e85:0000:0000:0000:12a4:04e0:ff33

IPv6 addresses don't need the zeroes at the beginning.

fe80:e85:0:0:0:12a4:4e0:ff33

You can leave out a bunch of zeros only one time for each place where they're together in a row.

fe80:e85::12a4:4e0:ff33

IPv4 is still the most commonly used format.

Internal IP Addresses

Every device connected to a network, whether through a cable or Wi-Fi, has a unique address called an IP address. These addresses are like phone numbers for devices on the network, ensuring that data goes to the right place. If two devices share the same IP address, it causes problems with sending and receiving information.

Internal IP addresses are used to find devices within your own network. They are like house numbers in a neighborhood, helping data get to the right device. These addresses aren't seen by computers outside your network, like the internet.

When a computer on your home or office network wants to talk to a distant computer, like a website, it asks a special device called a router for help. The router acts like a postman, making sure your computer's message reaches the faraway computer and that the reply comes back to your computer. It's like a middleman that helps your computer with its own private address talk to computers far away.

What Is a Dynamic IP Address?

A dynamic IP address is like a special number that your computer gets automatically when it connects to the internet through a router. Computers and laptops don't come with this number built-in; they need to get it from the router when they join the network. This can be a bit of a hassle, especially on big networks. Some devices, like routers, start with a common number (192.168.1.1), but you can switch it to fit your network better.

Now, something that's in every network device from the start is a MAC address. Think of it like a fingerprint for devices on the internet. These MAC addresses are one-of-a-kind and recognized worldwide.

Network routers keep a list of MAC addresses (like a device's ID) and IP addresses (like its internet address). When a device wants to send something to another device, it needs to know their IP address. The router helps by looking up this information and sending the data to the right place.

Before, people had to set up these addresses manually on their devices. But now, we have a way to do it automatically called DHCP (dynamic host configuration protocol).

In a network with DHCP, when a device joins, it basically says, "Hey, I'm new here. Can someone give me an IP address?" The router, which often acts as the DHCP server in home networks, says, "Sure, here's an address you can use, and here's some other info about the network."

If the device is okay with that address, it tells the router, "I like that address, I'll take it!" The router then says, "Great, it's yours," and confirms all the settings the device should use. This makes it easier for devices to join the network without needing manual setup.

Changing Dynamic IP Addresses

In simple terms, when a device wants to join a network, it needs an IP address and some details to work properly on that network. It's like getting a ticket to enter a party. But this ticket isn't forever; it's more like a rental. So, if the device wants to keep using that IP address, it has to ask for permission to keep it regularly. This permission comes in a message called DHCPOFFER, which also mentions how long the device can keep using the IP address.

Usually, there's no issue if the device gets the same IP address again and again. But imagine the device is turned off and doesn't ask for permission to keep using the IP address before its permission (lease) expires. In home networks, this lease often lasts for about 12 hours. In this case, the IP address can be given to a different device that wants to join the network. When the first device turns back on, it will be given a different IP address to use.

To see how all this happens on a Linux computer, you can use a command called "dhclient -v" with the "-v" option. It will show you the messages sent back and forth between your computer and the server that gives out IP addresses.

sudo dhclient -v

Changing Dynamic IP Addresses

We know the unique address of the computer's network card, and we can see messages where the computer asks for an IP address and gets one in response.

External IP Addresses

When you connect to the internet at home or in an office, your internet provider gives your network a special address, like a phone number, called an external IP address. This address is like your public face on the internet.

Your internet connection is like a bridge between your private network (your devices at home or work) and the big internet world. To make this bridge work, your internet router has two addresses. One is an inside address, like your home address, which helps your devices talk to each other on your network. The other is the outside address, which is the one your internet provider gives you, and it's like your router's passport to communicate with the internet.

Whenever you send or receive something on the internet, it goes through your router's outside address. So, this address is pretty important for all your internet traffic.

Internal IP addresses usually begin with numbers like 10, 172, or 192, while external IP addresses can have other numbers. Think of it like how a phone book helps you find phone numbers, but on the internet, DNS (Domain Name Service) turns website names into the right IP numbers so you can visit websites easily.

What Is a Static IP Address?

A static IP address is like a special address that doesn't change and isn't influenced by things like DHCP. When a device uses static IP addressing, it keeps the same IP address no matter how many times it's turned off and on or if it's not connected for a while.

Static vs. Dynamic IP Addresses

Using DHCP for assigning IP addresses automatically is convenient. However, there's one issue with DHCP. When a computer or any other device is turned off and then restarted, it might not always get the same IP address.

Most of the time, this isn't a problem. As long as your devices are connected to the network and can access the internet, it usually works fine. But sometimes, you have applications that need to communicate between computers, or you might have devices like a network attached storage (NAS) or media center that work best with fixed, unchanging IP addresses.

It's perfectly okay, and quite common, to have a mix of DHCP and static IP addressing on a network. DHCP makes it easy to give IP addresses to most devices, while static IP addressing is used for special cases when you want a device to always have the same IP address.

How to Assign an Internal Static IP Address on Your Computer

Setting a fixed IP address in Ubuntu is pretty simple. First, make sure you choose an IP address that no other device is using. You can use the ping command to check this.

Once you've picked your IP address, use the ncmli con add command to add a connection, and the nmcli con mod command to make it a fixed IP address. We have a step-by-step guide that shows you how. It also explains an easier way with pictures if you don't like typing commands.

You can also set fixed IP addresses on Windows 10 and 11 computers, and we can help with that too.

If you use containers like Docker, you can also give them fixed IP addresses.

How to Get an External Static IP Address

If your home internet router doesn't have a fixed external IP address, it might get a new one if it turns off and on again. Usually, this isn't a big deal. However, if you run your own online services and need to connect to them when you're not at home, having a fixed external IP address is important.

Your internet service provider (ISP) gives you your external IP address, and only they can change it. You can ask your ISP to give you a fixed external IP address for a small extra fee.

Having a fixed external IP address helps because you can easily reach your router and the devices on your home network from anywhere. It's like having a permanent address on the internet. It also makes it simpler to remember and share your connection with others. You can even buy a domain name and set it up to point to your fixed external IP address, making it easier for people to find your online services.

You can achieve the same result by using DDNS (Dynamic Domain Name System) routing. In this setup, you set up your router to talk to your DDNS service whenever it starts up or gets a new external IP address.

The DDNS service then updates the domain name associated with your website so that it always points to your latest external IP address. This way, when people try to access your website using your domain name, they'll always be directed to the correct external IP address, no matter how it changes.

Usually, Dynamic Is Sufficient

All you really need for your devices to work on your network are dynamic internal and external IP addresses. Your devices will automatically get unique addresses through a system called DHCP, so you don't need to stress about it.

If you want to make sure that a specific computer or device on your local network always has the same address, you can set it up with a fixed internal IP address.

And if you want to access your network from outside your home, you can either pay your internet provider for a consistent external IP address or use a DDNS service.

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