Which of the following is NOT a key component of a computer network?

A hardware warranty is not a key component of a computer network. In the context of networking, key components typically include elements that facilitate connectivity, communication, and functionality within the network.

Transmission media refers to the physical pathways through which data travels, such as cables or wireless signals, which are essential for establishing connections. Protocols define the rules and conventions for communication between devices, ensuring that data is transmitted and received correctly. Network services include various functions provided over the network, such as file sharing, email, and web services, which enhance the usability and functionality of the network.

In contrast, a hardware warranty is related to the terms of service and support for hardware components and does not directly contribute to the operation or structure of a computer network.