Nothing is more frustrating than turning on a computer and receiving a message that your Internet protocol (IP) address is already in use. In many cases, the process of identifying the name of the computer conflicting with your IP address is very straightforward. For Microsoft Windows users, learning one command can provide a simple method for troubleshooting many networking issues: the command "ping."
Verify the Problem
Verify that a system has an overlapping IP address. Simply reboot the computer that reported the problem to see whether or not it still reports the error about a conflicting IP address.
Access a Windows command prompt. To begin, click on the Windows logo on the task bar or Start and Run for a Windows XP operating system). Then type the command "cmd." Next, press the Enter key. This will open a Windows command prompt.
Look in the output of the command to identify the IP address assigned to your network interface. The important information will look similar to the following:
Wireless LAN adapter Wireless Network Connection: IPv4 Address........: 192.168.1.119
If the IP address begins with "169," an IP address was not assigned to the computer, and your network administrator can provide assistance.
If the address does not begin with "169," write down the IP address the system tries to use.
Turn off the computer.
Disconnect the computer from the network.
Type the command "ping -a" followed by the IP address in the command prompt window. For example, if the IP address you identified previously is "192.168.1.119," you would run this command: ping -a 192.168.1.119
Look at the output of the command. This will identify the name of the system with the IP address. An example of the output of the command is:
C:>ping -a 192.168.1.119
Pinging LoraP [192.168.1.119] with 32 bytes of data: Reply from 192.168.1.119: bytes=32 time<1ms TTL=128
Contact your network administrator for assistance if you cannot identify the computer using the IP address that was assigned to your computer.
If your network is configured to use dynamic IP addresses (DHCP), it should not have an IP address conflict.
If you still see a network IP conflict after an initial system reboot, contact a system administrator.