What type of address is used to identify a device on a network?

An IP address is essential for identifying a device on a network. It serves as a unique identifier that allows devices to send and receive data over the Internet or any IP-based network. Each device connected to the network must have a distinct IP address to ensure proper communication, akin to how a mailing address is required to send physical mail to a specific location. IP addresses can be classified as either IPv4 or IPv6, with IPv4 being the most commonly used, consisting of four sets of numbers (e.g., 192.168.1.1), while IPv6 provides a greater number of unique addresses using hexadecimals.

The other options serve different purposes: a URL is a reference to a resource, mainly used to access web pages, while a file name pertains to the storage location of files on devices. A port number, on the other hand, identifies specific services or applications on a device rather than the device itself. This distinction clarifies why the IP address is the appropriate answer for identifying devices on a network.