JNCIS-ENT · domain
IS IS
Practise Juniper Networks Enterprise Routing and Switching, Specialist (JNCIS-ENT, JN0-352) (JNCIS-ENT) IS IS practice questions — original exam-style scenarios with answer choices, explanations, and analysis of common mistakes.
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What to know about IS IS
IS IS questions test whether you can apply the concept in context, not just recognise a definition.
How the topic appears in realistic exam-style scenarios.
Which detail in the question changes the correct answer.
How to eliminate plausible but wrong options.
How to connect the question back to the wider exam objective.
Watch out for
Common IS IS exam traps
- ▸Answering from memory before reading the full scenario.
- ▸Missing a constraint such as cost, availability, security, scope or command context.
- ▸Choosing a broad answer when the question asks for the most specific fix.
- ▸Ignoring why the wrong options are tempting.
Question index
All IS IS questions (55)
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How do you configure an interface to be point-to-point when using IS-IS?
Medium2An administrator is configuring a new point-to-point link between two Junos routers running IS-IS. By default, how does IS-IS handle adjacency establishment on a point-to-point link compared to a broadcast link?
Medium3Which factors influence the DIS election on a broadcast link? (Choose TWO)
Hard4What happens if you have an area address mismatch in a Level 1 adjacency?
Medium5What is the purpose of the 'lsp-generation-interval'?
Easy6Which of the following are true regarding the IS-IS 'hello-interval'? (Choose TWO)
Medium7During an audit of an IS-IS routing network, an engineer examines the Type-Length-Value (TLV) structures used in IS-IS PDUs. Which TLV is specifically responsible for carrying IPv4 internal and external reachability information when using wide metrics?
Easy8Which TLV is used to carry IP prefixes in IS-IS?
Medium9During the examination of IS-IS packet captures on a multi-access LAN interface, an engineer notices a specific PDU type being transmitted periodically by the Designated Intermediate System (DIS) to maintain synchronized link-state databases. Which PDU type performs this function?
Easy10You want to influence the path selection for IS-IS traffic. You decide to change the metric. Which TLV is used to carry wide metrics?
Hard11Which of the following are true regarding IS-IS authentication? (Choose TWO)
Medium12Which command is used to verify the IS-IS adjacency state on a Junos device?
Easy13You have two routers connected via a point-to-point link. You need to ensure they form an IS-IS adjacency. Which configuration is required?
Easy14You have a Level 1/Level 2 router connecting two areas. How does it advertise itself to Level 1 routers?
Medium15Which of the following are valid IS-IS interface types? (Choose TWO)
Medium16You are configuring multi-topology IS-IS. What does this allow?
Hard17How does a router determine its System ID?
Medium18What does the 'show isis statistics' command reveal?
Medium19Which command allows you to view the IS-IS database summary?
Easy20What happens if you have an LSP with an expired lifetime?
Medium21Which actions occur during an IS-IS SPF calculation? (Choose THREE)
Hard22Which THREE statements are true regarding the Designated Intermediate System (DIS) election and its operational differences compared to OSPF's Designated Router (DR) election? (Choose three)
Hard23What is the effect of changing the reference bandwidth in IS-IS?
Medium24What are valid ways to configure IS-IS on a Junos interface? (Choose TWO)
Medium25Why would you set an interface to 'passive' in IS-IS?
Medium26An engineer needs to influence the DIS election on a multi-access broadcast segment running IS-IS on Junos devices. Which configuration parameter and hierarchy should the engineer modify to guarantee a specific router wins the DIS election?
Hard27You observe that an IS-IS adjacency is stuck in 'Initializing'. What is the most likely cause?
Medium28What are the consequences of a mismatch in metric style (narrow vs wide) between IS-IS neighbors? (Choose THREE)
Hard29Which level is enabled by default in Junos when configuring IS-IS on an interface?
Easy30What is the default behavior when an IS-IS router receives an LSP it already has?
Medium31In a multi-access network, which PDU is responsible for the DIS election?
Medium32You are troubleshooting a DIS election issue on a broadcast segment. What is the tie-breaker if the DIS priorities are equal?
Hard33Which of the following are true regarding IS-IS Level 1/Level 2 routers? (Choose TWO)
Medium34Which of the following scenarios would prevent an IS-IS adjacency from forming? (Choose TWO)
Medium35Which TWO characteristics describe the behavior and properties of Level 1 and Level 2 routing in IS-IS? (Choose two)
Easy36Which of the following is a valid IS-IS PDU type?
Easy37How does an IS-IS router identify the DIS in its hello packets?
Hard38You are observing that your IS-IS routers are not synchronizing their databases. You check the CSNP settings. What is the role of the CSNP on a broadcast segment?
Hard39Which of the following are valid ways to influence path selection in IS-IS? (Choose THREE)
Hard40Which of the following are true about CSNP and PSNP? (Choose THREE)
Hard41Which of the following is required for two routers to form a Level 2 adjacency?
Easy42When should you consider increasing the 'csnp-interval'?
Hard43Which command displays the IS-IS interface parameters?
Easy44Which of the following are valid IS-IS PDU types? (Choose THREE)
Medium45A network engineer wants to verify IS-IS link-state database entries, specifically checking for TLVs that carry extended IP reachability information with wide metrics. Which Junos operational command should be used?
Medium46What is the default IS-IS metric for an interface in Junos?
Easy47An engineer is troubleshooting IS-IS adjacency formation failures on a Junos device. Which THREE parameters must match or be compatible between neighboring routers to successfully establish an IS-IS adjacency? (Choose three)
Medium48When using authentication in IS-IS, where can you apply the password?
Hard49Which of the following are true about pseudonode LSPs? (Choose THREE)
Hard50You need to redistribute OSPF routes into IS-IS. Where do you configure this?
Hard51What is the function of the DIS in an IS-IS broadcast network?
Medium52An engineer needs to configure a Junos device to operate in an IS-IS routing domain where the router should connect both Level 1 and Level 2 areas, forming a boundary between them. Which configuration command under the [edit protocols isis interface] hierarchy correctly enables dual-level operations on the interface?
Medium53What is the purpose of the 'lsp-lifetime' command?
Hard54A network administrator troubleshooting an IS-IS adjacency issue notices that two routers are failing to form an adjacency over a point-to-point link. One router has wide metrics enabled globally, while the other router has wide metrics disabled and only supports narrow metrics. Which parameter or feature must be matching or handled for IS-IS link-state PDUs to be successfully processed between these neighbors?
Hard55Which of the following are true about IS-IS Level-1 and Level-2 areas? (Choose TWO)
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Frequently asked questions
- What does the IS IS domain cover on the JNCIS-ENT exam?
- IS IS questions test whether you can apply the concept in context, not just recognise a definition.
- How many questions are in this domain?
- This page lists all 55 IS IS questions in the JNCIS-ENT question bank. The actual exam draws from this domain proportionally to its weighting in the official exam blueprint.
- What is the best way to practise this domain?
- Start with a short focused session (10 questions) to identify gaps, then work through explanations. Repeat with a longer session once the weak areas feel solid.
- Can I practise only IS IS questions?
- Yes — the session launcher on this page filters questions to this domain only. Choose any session length for inline explanations and scoring.