IP cameras can usually be configured for either static or dynamic (DHCP) IP addresses. If a static IP address was configured on an IP camera and forgotten, or if the IP address has been configured dynamically and is needed in order to view video, there are a few procedures you can use to quickly find the address of the IP camera.
Turn off all computers and peripheral devices plugged into the same network as the IP camera (with the exception of the network switch or router connected to the IP camera).
Plug a Linux computer into the same network switch as the IP camera, them reboot the Linux computer. Open a command line terminal on the Linux computer and type "ping -b 192.168.1.255" replacing the "192.168.1.255" with the last IP address in the range of IP addresses on the network.
The output received on the command line will include a small number of IP addresses from any devices that remain connected and running on the network, including the IP camera. Try viewing video from the IP camera using each address, and you will find the IP address of the camera.
Login to the router connected to the IP camera from a web browser such as Firefox or Internet Explorer, using the default username and password (or a custom username and password if so configured). Navigate through the administration web pages of the router and find the list of "connected devices" or the list of "DHCP clients". Either list will contain the IP address of the IP camera.
Login to the DHCP server on the network (if using a standalone DHCP server), then navigate to and search through the list of DHCP clients that are registered and find the Media Access Control (MAC) address of the IP camera in the list. The IP address of the camera will be listed in association with the IP address of the camera.