TestOut LabSim A+ Certification Practice Exam

Which network topology is the most susceptible to a single point of failure?

1. Mesh

2. Star

3. Bus

4. Ring

The correct answer is: Bus

The bus topology is most susceptible to a single point of failure because it relies on a single central cable (the bus) to connect all devices in the network. In a bus topology, if the main cable fails at any point, all devices connected to that cable lose their ability to communicate, resulting in network downtime. This inherent dependency on one main cable creates a significant vulnerability—if that cable is damaged or disconnected, the entire network can be rendered inoperable. In contrast, other topologies, such as mesh or star, have additional pathways or connections that can help mitigate the impact of a failure. For example, in a star topology, all devices are connected to a central hub or switch. While the hub represents a single point of failure, the rest of the network remains operational if one of the individual connections fails. Similarly, in a mesh topology, multiple pathways between devices mean that if one connection fails, data can still be routed through alternate paths, maintaining network functionality. The ring topology is less susceptible as well since each device is connected to two others, allowing for a more resilient structure compared to the bus topology. Thus, the bus topology's reliance on a single cable is what makes it particularly vulnerable to failure.