N10-009 Question 139
Single answer2.1 Explain characteristics of routing technologies.A company has a headquarters location and 18 branch offices connected over WAN links. The network team wants routers to automatically learn routes, converge quickly after a link failure, and scale without sending full routing tables every 30 seconds. The company also wants to avoid the 15-hop limitation that affected its previous design. Which routing technology best meets these requirements?
- A
RIP
- B
Static routing
- C
OSPF
- D
Default routing
Show answer and explanation
Correct answer: C
Explanation
The best answer is OSPF because the scenario specifically calls for a dynamic routing protocol that scales well, converges quickly, and avoids RIP's known limitations. OSPF is a link-state protocol that uses the SPF algorithm to calculate optimal paths and reacts efficiently to topology changes. By contrast, RIP is a distance-vector protocol with a 15-hop maximum and slower convergence, making it a poor fit for a distributed enterprise WAN. Static routing and default routing can be useful in certain designs, especially small networks or stub networks, but they do not provide the automated, scalable route learning required here. This aligns with common networking best practices and vendor documentation from sources such as Cisco and Juniper, which position OSPF as an appropriate interior gateway protocol for medium-to-large enterprise networks.
- A. Incorrect.
RIP is incorrect because, although it is a dynamic routing protocol, it uses hop count as its metric, has a maximum hop count of 15, and typically sends periodic full routing updates. In a multi-site WAN environment, those characteristics limit scalability and slow convergence compared to more modern protocols. A candidate might choose RIP because it does provide automatic route learning, but it does not satisfy the stated scalability and convergence requirements.
- B. Incorrect.
Static routing is incorrect because it does not automatically learn routes or dynamically adapt well to link failures in a network with many branch offices. Static routes can work in small, stable environments, but managing them across 18 branches would create significant administrative overhead and increase the risk of misconfiguration. Someone might select this option because static routes reduce protocol overhead, but they do not provide the resiliency and automatic convergence described in the scenario.
- C. Correct.
OSPF is correct because it is a link-state dynamic routing protocol designed for larger, more complex networks. It converges faster than RIP, does not have RIP's 15-hop limitation, and scales better by exchanging link-state information and updates triggered by topology changes rather than relying on frequent full-table broadcasts. OSPF is commonly used in enterprise WAN environments where rapid adaptation and scalability are required.
- D. Incorrect.
Default routing is incorrect because it is a routing approach used to send traffic toward a next-hop router when no more specific route exists; it is not, by itself, a dynamic routing technology that learns complete network paths or provides rapid convergence across many interconnected sites. A candidate might choose this option because default routes are useful in branch environments, but they do not meet the scenario's requirement for dynamic, scalable route exchange throughout the enterprise.