Cisco Certified Network Associate (CCNA) Practice Exam

What are two drawbacks of link-state routing protocols? (Choose two)

1. The large size of routing tables

2. High volume of link-state advertisements

3. The requirement for a linear topology

4. High demand on router resources

The correct answer is: The requirement for a linear topology

Link-state routing protocols indeed have several drawbacks, and two particularly notable ones are the high volume of link-state advertisements and the high demand on router resources. Link-state routing protocols work by having each router maintain a complete and up-to-date map of the network topology. To achieve this, routers must send link-state advertisements (LSAs) to inform all other routers about the state of their links. This results in a significant amount of network traffic, especially in large networks, as routers continuously share their state information. Thus, the high volume of link-state advertisements can lead to increased bandwidth usage and require more efficient handling to prevent performance degradation. Additionally, link-state protocols demand considerable resources from routers, including CPU power and memory. Each router needs to process multiple LSAs, calculate its own routing tables based on the complete network topology, and maintain the state of the network. This can become resource-intensive, particularly in large networks with many routers, potentially leading to slower performance or requiring more powerful hardware. In this context, while a linear topology is not a requirement for link-state routing protocols, the other two aspects mentioned reflect significant challenges they pose in practical scenarios.