There can be occasions when it is beneficial to use fixed IP addresses, for example when wireless connections are dropped frequently and the IP address isn’t automatically renewed. They shouldn’t be used when a wireless adapter cannot connect to a router to get its IP address, because this simply hides the fact that there is a problem between adapter and router.

To allocate fixed IP addresses you must firstly establish what the router's own IP address is, because all connected computers must be in the same Subnet (IP address range) as the router, but have a unique address in the network. If you don’t know the router’s IP address then, using a computer that is connected to the router, open a Command Prompt window (“Start > Run”, type cmd and click OK) and, at the prompt, type:

ipconfig /all and press Enter.

This will display details of all network adapters in the PC. Look for the Default Gateway address, which will be the router’s IP address:



Now go into the Network Connections folder:

In XP, go to “Control Panel > Network Connections”.

In Vista, go to “Control Panel > Network and Sharing Center” then click the link at the left to “Manage network connections”.

Alternatively, in either version of windows, you can open the Network Connections folder directly by going to “Start > Run”, typing ncpa.cpl and clicking OK.

Right click the adapter, “Local Area Connection” or “Wireless Network Connection", that you want to allocate a fixed IP address to and select Properties.

In XP, highlight the entry for “Internet protocol (TCP/IP)" and click the Properties button.

In Vista, highlight the entry for “Internet Protocol Version 4 (TCP/IPv4)” and click the Properties button.

In the TCP/IP Properties sheet that opens, click the option to “Use the following IP address”, which will automatically also enable the option “Use the following DNS server addresses". The address you use must have the first three octets (numbers) the same as those of the router (in my example 192.168.3) and the final octet must be an unused number in the range 1 to 254. As a router normally uses the “1”, the remaining available addresses are 2 to 254. Therefore, using my example of a router with the address 192.168.3.1, type in:

IP address – 192.168.3.2

Subnet Mask – 255.255.255.0

Default Gateway – 192.168.3.1 (the router’s IP address)

DNS Server address – 192.168.3.1 (the router’s IP address)

Each computer in the network must have a different IP address but all have the same Subnet Mask, Default Gateway and DNS Server addresses.



To revert to automatic IP addressing, return both settings to automatic:

Obtain an IP address automatically
Obtain DNS server address automatically

You can use fixed DNS Server addresses with automatic IP addresses, but if the IP address is entered manually, the DNS addresses must also be entered manually.