How to set up a static IP address in Windows XP

Your computer's IP address is what identifies it on your network. An IP address is like a phone number, uniquely identifying that device so other devices can communicate with it. IP addresses can be either static or dynamic.

Most computer networks use a DHCP (Dynamic Host Configuration Protocol) server to hand out and manage IP addresses. These IP addresses are considered dynamic, because they are only temporary -- after a set amount of time, the lease expires and that IP address is thrown back into the pool to be used by another device.

A Windows XP computer can be set up with a static IP address -- one that doesn't change, even when your computer has been off for an extended time -- with a few simple steps. However, using a static IP address can be tricky, because you need to know which IP addresses are available to use. If you pick an IP address outside the range your network recognizes, your computer won't be able to connect to any other devices, including your router or switch. If you are on a business network, talk to your network administrator before setting up a static IP address. If you are on a home network, check your router's settings to see what range of IP addresses the router uses.

If you currently have a dynamic IP address, you can use that one as your static IP address.  If you're going to pick a new static IP address, try to pick one outside the range of IP addresses that your DHCP server hands out.  For example, if your DHCP server uses the IP addresses from 192.168.1.100 to 192.168.1.150, then you could pick an IP address such as 192.168.1.170.  When picking an IP address, be sure not to pick one that's in use by another computer or device. Using the same IP address for more than one device will cause connection problems.

Once you are sure you want to switch to a static IP address and you have an address picked out, changing the settings is easy. Access the Network Connections window, either by right-clicking on My Network Places (on the desktop or in the Start menu) and choosing Properties, or through the Control Panel. Then choose the connection you want to give a static IP address to (such as "Local Area Connection").  Scroll down the list of services until you get to "Internet Protocol (TCP/IP)." Click Properties, and a dialogue box will pop up.

If you currently use DHCP and dynamic IP addresses, the radio button next to "Obtain an IP address automatically" is selected. To change to a static IP address, click the button underneath it ("Use the following IP address"). Input the IP address you plan on using, as well as the subnet mask and gateway address. (The subnet mask is most likely 255.255.255.0 if you are on a home network, and the gateway address will be your router's IP address.)

In order to connect to the Internet, you'll need a DNS (Domain Name System) server. Hopefully your router can perform this function; type your router's IP address next to "Preferred DNS server."

Once you click OK to close out any open windows and save your changes, your computer will assume the new IP address. To verify that Windows applied the change, go back into the command prompt and run "ipconfig" again; you should see the new IP address displayed. Next to the line marked "DHCP enabled" it should now say no instead of yes.

Your computer now has a static IP address. Assuming there is no conflict with any other devices, and assuming the IP address (and other information) you input is valid, your computer will now keep that IP address until you tell it otherwise. To re-enable DHCP, simply go back into the network properties and click the appropriate radio button. (You'll also want to re-enable "Obtain DNS server address automatically.")

(Originally posted on Helium.com, October 2009)