Finding a device on a network, especially when the network uses dynamic IP addresses, can be a difficult task when you do not have access to network devices such as routers, switches and the DHCP server that is assigning the IP addresses. However, by using one simple tool and the MAC address of the device for which you need to find the IP address, you can obtain the IP address in minutes.
Click the "Start" button the click the "Run" box (if using Windows XP) or "Search" box (if using Windows Vista or 7) and type "cmd" and then press the "Enter" key.
Type "ping hostname," replacing "hostname" with the hostname of the device or computer for which you need the IP address, and then press the "Enter" key.
Type "arp –a" and press the "Enter" key. View the output displayed, and the IP address of the device or computer will be listed in association with the MAC address of the same device or computer.