A field service technician replaces a piece of AV equipment on the client LAN, but it isn't receiving a proper IP address. What is the most likely issue?

The most likely issue in this scenario is that the new piece of equipment needs to have its MAC address registered.

In many network configurations, particularly in managed networks, devices must be registered on the network to ensure they are assigned an appropriate IP address. This could involve adding the MAC address of the new equipment to a whitelist or allowing it through a network access control system. If the MAC address has not been registered, the network may prevent the device from obtaining an IP address through DHCP (Dynamic Host Configuration Protocol), resulting in the problem described.

The other options, while they may represent possible issues in different contexts, do not directly pertain to the inability of a device to receive an IP address from the client LAN. For instance, a defective USB port would not usually affect network connectivity and would instead relate to physical connections for devices that rely on USB interfaces. Likewise, the requirement for HDCP (High-bandwidth Digital Content Protection) does not impact IP addressing but concerns content security between devices. Finally, firmware discrepancies could affect functionality or compatibility but would not inherently prevent a device from obtaining an IP address unless the firmware specifically prevents network interaction due to configuration issues.