SPF Algorithm JN0-664 Practice Questions (Page 4)

Questions 16–20

1. 16foundation · easy

   In Dijkstra's algorithm as used by OSPF, what is the first step after initializing the tree list with the local router?

   • ACalculate the cost to all destinations in the link-state database
   • BPlace all neighbors of the local router into the candidate list with their path costs
   • CFlood the local router's LSA to all neighbors
   • DMove the router with the lowest router ID from the candidate list to the tree list
   Reveal Solution Discussion Select an answer first
2. 17foundation · easy

   What happens to a node in the candidate list if a lower-cost path to it is discovered during SPF computation?

   • AThe node is immediately moved to the tree list
   • BThe node is added a second time with the new cost
   • CThe node is removed from the candidate list permanently
   • DThe node's entry is updated with the new lower cost and the predecessor is changed
   Reveal Solution Discussion Select an answer first
4. 18application · medium

   An OSPF router experiences a flapping link that causes repeated LSUs and SPF runs. The network operator wants to reduce the CPU impact of these frequent topology changes while still converging quickly when the network stabilizes. What should the operator configure?

   • ASPF throttling timers with a short initial delay and a longer maximum wait
   • BDisable SPF entirely and rely on static routes
   • CIncrease the OSPF hello interval to 60 seconds
   • DA single fixed SPF delay of 5 seconds
   Reveal Solution Discussion Select an answer first
5. 19application · medium

   An OSPF router is about to run the SPF algorithm. Which data does the router use as input to this computation?

   • AThe OSPF neighbor table, containing only adjacent routers
   • BThe forwarding table, containing next-hop information
   • CThe routing table, containing only the best routes
   • DThe link-state database, containing all routers and links in the area
   Reveal Solution Discussion Select an answer first
6. 20expert · hard

   A network engineer is troubleshooting a routing loop in an OSPF network. The engineer suspects that the SPF algorithm has produced a loop due to a misconfiguration. Which statement accurately describes the role of the SPF algorithm in loop prevention?

   • AThe SPF algorithm guarantees loop-free paths by constructing a tree where each node has a single parent
   • BThe SPF algorithm uses a separate loop-detection mechanism
   • CThe SPF algorithm can produce loops if the link-state database is inconsistent
   • DThe SPF algorithm relies on the router ID to break ties and prevent loops
   Reveal Solution Discussion Select an answer first