What unique ID number, coordinated by the Institute of Electrical and Electronics Engineers, is used by only one network interface card worldwide?

The unique ID number coordinated by the Institute of Electrical and Electronics Engineers that is used by only one network interface card worldwide is the Media Access Control address (MAC). Each network interface card (NIC) is assigned a MAC address that is intended to be globally unique, ensuring that no two devices on the same network (or the internet) will have the same address. This unique identifier is crucial for network communications, allowing devices to identify and locate each other within local networks.

On the other hand, the Internet Protocol address (IP) is not unique to an individual NIC; instead, it can change depending on the network configuration. The Network File System (NFS) is a protocol used for file sharing, while the Dynamic Host Configuration Protocol (DHCP) is a method for dynamically assigning IP addresses to devices on a network and does not pertain to the unique identification of NICs. Thus, MAC addresses serve the essential purpose within networking to prevent collisions and ensure correct data routing to the intended hardware.