Line Topology

Correct Answer: Single point of failure

In a bus network topology, all computers are connected in a single line using a common backbone called a 'bus'. The problem with this type of network is that if any part of the network goes down, the entire network fails. This issue is commonly referred to as a 'single point of failure,' which is likely to be the cause of the company's frequent network issues. The other answers are wrong. 'Multiple collision domains' would not be a problem in a bus network topology as all devices share the same data path. 'Excessive retransmissions due to star topology' is irrelevant as the company uses a bus topology. 'Mismatched duplex settings' would cause problems in an Ethernet network, but there's no indication that this is the case here.

Correct Answer: Switch to a star topology

The best solution to address the network performance decrease caused by an increase in the number of devices in a ring topology network configuration is to 'Switch to a star topology'. This allows each device to have a direct connection to a central node (typically a switch or a hub) which can handle much larger quantities of data and number of devices than a ring topology, hence, improving the performance. The other answers are incorrect because 'Adding additional hubs' would create unnecessary complexity and wouldn't inherently fix the core issue in a ring topology - each device's reliance on the previous for information transfer. 'Replacing copper cables with fiber-optic cables' might improve some performance aspects but that suggests an issue with transmission medium not the topology itself. Lastly, 'Enable multicast preemption' is irrelevant as multicast preemption is a technology mostly used in wireless networks to improve transmission quality and has little or no impact on a ring topology's performance.

Correct Answer: Bus topology

The best choice in terms of minimizing cabling costs would be the Bus topology. The bus topology is the simplest and least expensive topology. It requires the least amount of cable as each computer or network device is directly connected to a single common cable, also known as the bus. In contrast, ring topology would require more cabling as each device is connected to two other devices, forming a ring. Star topology would require even more cabling, as each device needs to be connected to a central device like a hub or switch. Lastly, mesh topology is not a correct answer because it would require the most cabling since every device is connected to every other device.