A service provider network runs IS-IS with narrow metrics. Router R1 has four links to R2, each with a metric of 10. R1 also has a single link to R3 with a metric of 5, and R3 has a single link to R2 with a metric of 5. The SPF calculation on R1 is considering the path to R2. How many equal-cost paths will R1 install in its routing table for the route to R2's loopback?

One path, selected by the lowest next-hop IP

Five paths (four direct and one via R3)

Four paths via the direct links only

A network engineer is troubleshooting a routing loop that occurs after a link failure in an IS-IS network. The engineer suspects that the SPF calculation on some routers is using stale information. What is the most likely cause of this issue?

The routers are using wide metrics instead of narrow metrics

The routers are using partial route computation (PRC) instead of full SPF

The failed link's LSP has not yet been flooded to all routers

The SPF timer is set too low, causing frequent recalculations

In the SPF algorithm, what does the shortest path tree represent?

The physical topology of all links in the network

The list of all routers in the IS-IS domain

The set of all LSPs in the link-state database

The optimal paths from the local router to all other routers in the area

Which data structure does the SPF algorithm use to track the next router to process during tree construction?

A linked list of all interfaces

A priority queue of candidate nodes

A hash table of LSP sequence numbers

What does IS-IS do when the SPF algorithm finds multiple paths to the same destination with equal total cost?

It selects the path with the lowest next-hop IP address

It randomly selects one path and discards the others

It selects the path with the highest bandwidth

It installs all equal-cost paths in the routing table for load balancing

Juniper NetworksCertified Professional, Service Provider Routing and Switching (JNCIP-SP)

Domain 2Objective 5

SPF Algorithm JN0-664 Practice Questions (Page 4)

Part of the IS-IS domain, which makes up ~18% of our current practice bank. Juniper Networks does not publish an official question count, but from its 90-minute exam (~35–60 total, ~6–11 in this domain), expect 1–1 from this objective — we provide 21 practice questions to prepare you well beyond it. (estimate)

21questions here

5free pages

6concepts

Questions 16–20

16application · medium
A service provider network runs IS-IS with narrow metrics. Router R1 has four links to R2, each with a metric of 10. R1 also has a single link to R3 with a metric of 5, and R3 has a single link to R2 with a metric of 5. The SPF calculation on R1 is considering the path to R2. How many equal-cost paths will R1 install in its routing table for the route to R2's loopback?
Select an answer first
17application · medium
A network engineer is troubleshooting a routing loop that occurs after a link failure in an IS-IS network. The engineer suspects that the SPF calculation on some routers is using stale information. What is the most likely cause of this issue?
Select an answer first
18foundation · easy
In the SPF algorithm, what does the shortest path tree represent?
Select an answer first
19foundation · easy
Which data structure does the SPF algorithm use to track the next router to process during tree construction?
Select an answer first
20foundation · easy
What does IS-IS do when the SPF algorithm finds multiple paths to the same destination with equal total cost?
Select an answer first

Finished these 5 questions?

Review the revealed explanations, or continue through the curriculum.

Next 5 questions →Back to JN0-664

Free Basic Practice is a study aid with revealable answers — not a scored exam. Examers.io is independent and not affiliated with or endorsed by Juniper Networks. “JN0-664” is a trademark of its owner, used for identification only.