Static IP Address - Dynamic IP Address [ Windows - Linux ]

What is a Static IP Address?

A static IP address is an IP address that was manually configured for a device, versus one that was assigned via a DHCP server. It's called static because it doesn't change. It's the exact opposite of a dynamic IP address, which does change.

Routers, phones, tablets, desktops, laptops, and any other device that can use an IP address can be configured to have a static IP address. This might be done through the device giving out IP addresses (like the router) or by manually typing the IP address into the device from the device itself.

Static IP addresses are also sometimes referred to as fixed IP addresses or dedicated IP addresses.

Why Would You Use a Static IP Address?

Another way to think of a static IP address is to think of something like an email address, or a physical home address. These addresses don't ever change - they're static - and it makes contacting or finding someone very easy.

Similarly, a static IP address is useful if you host a website from home, have a file server in your network, are using networked printers, are forwarding ports to a specific device, are running a print server, or if you use a remote access program. Because a static IP address never changes, other devices always know exactly how to contact a device that uses one.

For example, say you set up a static IP address for one of the computers in your home network. Once the computer has a specific address tied to it, you can set up your router to always forward certain inbound requests directly to that computer.

Not using a static IP address (using a dynamic IP that does change) would become a hassle if you're hosting a website, for example, because with every new IP address that the computer gets, you'd have to change the router settings to forward requests to that new address. Neglecting to do this would mean nobody could get to your website because your router has no idea which device in your network is the one that's serving the website.

Another example of a static IP address at work is with DNS servers. DNS servers use static IP addresses so that your device always knows how to connect to them. If they changed often, you'd have to regularly reconfigure those DNS servers on your router or computer to keep using the internet like you're used to.

Static IP addresses are also useful for when the device's domain name is inaccessible. Computers that connect to a file server in a workplace's network, for instance, could be set up to always connect to the server using the server's static IP instead of its hostname. Even if the DNS server is malfunctioning, the computers could still access the file server because they'd be communicating with it directly through the IP address.

With remote access applications like Windows Remote Desktop, using a static IP address means you can always access that computer with the same address. Using an IP address that changes will, again, require you to always know what it changes to so that you can use that new address for the remote connection.

Static vs Dynamic IP Addresses

The opposite of a never-changing static IP address is an ever-changing dynamic IP address. A dynamic IP address is just a regular address like a static IP is, but it's not permanently tied to any particular device.

Instead, they're used for a specific amount of time and then returned to an address pool so that other devices can use them.

This is one reason that dynamic IP addresses are so useful. If an ISP were to use static IP addresses for all of their customers, that would mean that there'd constantly be a limited supply of addresses for new customers. Dynamic addresses provide a way for IP addresses to be reused when they're not in use elsewhere, providing internet access for many more devices than what would otherwise be possible.

Static IP addresses limit downtime. When dynamic addresses obtain a new IP address, any user that's connected to the existing one will be kicked off from the connection and have to wait to find the new address.

This wouldn't be a wise setup to have if the server is hosting a website, a file sharing service, or an online video game, all of which normally require constantly active connections.

The public IP address assigned to the routers of most home and business users is a dynamic IP address. Larger companies usually do not connect to the internet via dynamic IP addresses; instead, they have static IP addresses assigned to them which do not change.

Disadvantages of Using a Static IP Address

The major disadvantage that static IP addresses have over dynamic addresses is that you have to configure the devices manually. The examples I gave above with regards to a home web server and remote access programs require you not only to set up the device with an IP address but also to properly configure the router to communicate with that specific address.

This definitely requires more work than just plugging in a router and allowing it to give out dynamic IP addresses via DHCP.

What's more is that if you assign your device with an IP address of, say, 192.168.1.110, but then you go to a different network that only gives out 10.X.X.X addresses, you will not be able to connect with your static IP and will instead have to reconfigure your device to use DHCP (or pick a static IP that works with that new network).

Security might be another downfall to using static IP addresses. An address that never changes gives hackers a prolonged time frame to find vulnerabilities in the device's network. The alternative would be using a dynamic IP address that changes and would, therefore, require the attacker to also change how it is communicating with the device.

How to Set a Static IP Address in Windows

The steps for configuring a static IP address in Windows are fairly similar in Windows 10 through Windows XP. See this guide at How-To Geek for specific instructions in each version of Windows.

Some routers let you reserve an IP address for specific devices that are connected to your network. This is normally done through what's called DHCP Reservation, and it works by associating an IP address with a MAC address so that each time that specific device requests an IP address, the router assigns it the one you've chosen to have associated with that physical MAC address.

You can read more about using DHCP Reservation at your router's manufacturer's website. Here are links to instructions on doing this on D-Link, Linksys, and NETGEAR routers.

What is a Dynamic IP Address?

A dynamic IP address is an IP address that's automatically assigned to each connection, or node, of a network, like your smartphone, desktop PC, wireless tablet... whatever.

This automatic assignment of IP addresses is done by what's called a DHCP server.

A DHCP server assigned IP address is called dynamic because it will often be different on future connections to the network.

The "opposite" of a dynamic IP address is called a static IP address (one that was configured manually).

Where Are Dynamic IP Addresses Used?

The public IP address that gets assigned to the router of most home and business users by their ISPs is a dynamic IP address. Larger companies usually do not connect to the Internet via dynamic IP addresses and instead have static IP addresses assigned to them, and only them.

In a local network like in your home or place of business, where you use a private IP address, most devices are probably configured for DHCP, meaning that they're using dynamic IP addresses. If DHCP is not enabled, each device in you home network would need to have network information manually setup, so you'd probably already be well aware of this.

Note: Some Internet Service Providers assign "sticky" dynamic IP addressees that do change, just less frequently than a typical dynamic IP address.

What are the Advantages of Dynamic IP Addresses?

Frankly, the main advantage of assigning IP addresses dynamically is that it's more flexible, and easier to setup and administer, than static IP address assignments.

For example, one laptop that connects to the network can be assigned a particular IP address, and when it disconnects, that address is now free to be used by another device that connects later on, even if it's not that same laptop.

With this type of IP address assignment, there's little limit to the number of devices that can connect to a network since ones that don't need to be connected can disconnect and free up the pool of available of addresses for another device.

The alternative would be for the DHCP server to set aside a particular IP address for each device, just in case it wanted to connect to the network. In this scenario, a few hundred devices, no matter if they were being utilized or not, would each have their own IP address which could limit access for new devices.

As I mentioned above, another advantage of using dynamic IP addresses is that it's easier to implement than static IP addresses. Nothing needs to be setup manually for new devices that connect to the network... all you have to do is make sure DHCP is enabled on the router.

Since almost every network device is configured by default to to grab an IP address from the available pool of addresses, everything is automatic.

What are the Disadvantages of Dynamic IP Addresses?

While it's extremely common, and technically acceptable, for a home network to use a dynamically assigned IP address for its router, a problem arises if you're trying to access that network from an outside network.

Let's say your home network is assigned a dynamic IP address by your Internet Service Provider but you need to remotely access your home computer from your work computer.

Since most remote access/desktop programs require that you know the IP address of your router to get to the computer inside that network, but the IP address of your router changes periodically because it's dynamic, you could run in to trouble.