Wired and Wireless Networks

Correct Answer: Router

A router is a device that is used to connect different networks together. It facilitates the process of data transmission over the internet by selecting the most efficient path for the data to reach its destination. On the other hand, a switch is used to connect devices within the same network and not different networks. A hub is a simple device that connects computers in a network without offering any routing capabilities. A firewall, while essential for network security, does not connect networks but rather inspects and filters incoming and outgoing network traffic based on an organization's previously established security policies.

Correct Answer: Star topology

The network topology that connects each device to a central hub or switch is the Star topology. In this topology, each device has a dedicated point-to-point link only to the central controller, referred to as the hub. The hub acts as an exchange: if one device wants to send data to another, it sends the data to the hub, which then relays the data to the other connected device. The advantages of a star topology are that it's simple to set up and manage, and if one link fails, only that link is affected, not the entire network. As for the other answers, Bus topology is not correct because in this topology, all devices are connected to a central cable, called the bus or backbone, rather than a hub. Ring topology is not correct because in this topology, each device has a dedicated point-to-point connection with only the two devices on either side of it in a closed loop, forming a 'ring', and there is no central hub. Mesh topology is not correct because in a mesh network, devices are interconnected, with some devices connected to all the others. But there is no central hub.

Correct Answer: Single-mode

The fiber-optic cable with a diameter of 9 microns is a Single-mode fiber. This type of fiber is designed to carry only a single ray of light, making it ideal for long-distance transmissions as there is less signal degradation. In contrast, Multi-mode fibers have a larger core diameter and support multiple paths of light, leading to more signal degradation over long distances, making them unsuitable for our case. Coaxial and Twisted-pair are not types of fiber-optic cables, so they do not apply to this question.