List one common tool used for installing Ethernet cables.

A cable crimper is commonly used for installing Ethernet cables because it allows the technician to attach connectors, such as RJ45 plugs, to the ends of the cables. This process is essential for creating a functional Ethernet connection, as the crimper ensures that the connectors are securely fastened and making the right electrical connections for data transmission.

The other tools listed do serve important purposes in networking and telecommunications but are used for different tasks. A coaxial cable cutter is specifically meant for cutting coaxial cables, which are not utilized in Ethernet installations. A signal meter is used to measure the strength and quality of signals in networks, rather than for the physical installation of cables. Lastly, a fiber optic tester is employed to assess the functionality and performance of fiber optic cables, which are distinct from Ethernet cables and utilize different types of connectors. Therefore, the cable crimper stands out as the most relevant tool for directly installing Ethernet cables.