SPF Algorithm JN0-664 Practice Questions (Page 5)

Questions 21–25

1. 21foundation · easy

   What is the default behavior of OSPF when multiple equal-cost paths exist to the same destination?

   • AIt marks the destination as unreachable to avoid loops
   • BIt installs all equal-cost paths and load-balances traffic across them
   • CIt selects only the path learned first
   • DIt selects only the path with the lowest next-hop router ID
   Reveal Solution Discussion Select an answer first
2. 22application · medium

   A service provider has four parallel links between two OSPF routers, each with a cost of 10. The network operator wants to load-balance traffic across all four links. What is the default OSPF behavior in this scenario?

   • AOSPF installs all four links as ECMP next hops and load-balances across them
   • BOSPF selects only one link based on the lowest interface index
   • COSPF installs two links and ignores the other two
   • DOSPF selects only one link based on the highest bandwidth
   Reveal Solution Discussion Select an answer first
4. 23application · medium

   A network administrator is configuring a new OSPF area and wants to understand how the SPF algorithm will determine the best path to a remote network. The administrator knows that OSPF uses a cost metric. What does the SPF algorithm use as the cost of a path?

   • AThe bandwidth of the slowest link along the path
   • BThe delay of the path as measured by probes
   • CThe number of hops along the path
   • DThe sum of the interface costs along the path
   Reveal Solution Discussion Select an answer first
5. 24application · medium

   An OSPF router is running SPF after a topology change. The router has placed its own router ID in the tree list and all directly connected neighbors in the candidate list. The router now examines the candidate list and selects the entry with the lowest cost. What is the next step in the Dijkstra computation?

   • AAdd the selected entry to the tree list and stop the computation
   • BCompare the selected entry with all tree-list entries and keep the lower cost
   • CMove the selected entry to the tree list and add its neighbors to the candidate list
   • DRemove the selected entry from the candidate list and discard it
   Reveal Solution Discussion Select an answer first
6. 25foundation · easy

   What is the primary benefit of Incremental SPF (iSPF) compared to full SPF?

   • AIt reduces CPU usage by recomputing only the affected parts of the shortest-path tree
   • BIt increases the number of ECMP paths that can be installed
   • CIt reduces the memory required to store the link-state database
   • DIt eliminates the need to flood LSAs after a topology change
   Reveal Solution Discussion Select an answer first