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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.

55 questions12 easy25 medium18 hard

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What this domain covers

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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1

How do you configure an interface to be point-to-point when using IS-IS?

Medium
2

An 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?

Medium
3

Which factors influence the DIS election on a broadcast link? (Choose TWO)

Hard
4

What happens if you have an area address mismatch in a Level 1 adjacency?

Medium
5

What is the purpose of the 'lsp-generation-interval'?

Easy
6

Which of the following are true regarding the IS-IS 'hello-interval'? (Choose TWO)

Medium
7

During 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?

Easy
8

Which TLV is used to carry IP prefixes in IS-IS?

Medium
9

During 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?

Easy
10

You want to influence the path selection for IS-IS traffic. You decide to change the metric. Which TLV is used to carry wide metrics?

Hard
11

Which of the following are true regarding IS-IS authentication? (Choose TWO)

Medium
12

Which command is used to verify the IS-IS adjacency state on a Junos device?

Easy
13

You have two routers connected via a point-to-point link. You need to ensure they form an IS-IS adjacency. Which configuration is required?

Easy
14

You have a Level 1/Level 2 router connecting two areas. How does it advertise itself to Level 1 routers?

Medium
15

Which of the following are valid IS-IS interface types? (Choose TWO)

Medium
16

You are configuring multi-topology IS-IS. What does this allow?

Hard
17

How does a router determine its System ID?

Medium
18

What does the 'show isis statistics' command reveal?

Medium
19

Which command allows you to view the IS-IS database summary?

Easy
20

What happens if you have an LSP with an expired lifetime?

Medium
21

Which actions occur during an IS-IS SPF calculation? (Choose THREE)

Hard
22

Which 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)

Hard
23

What is the effect of changing the reference bandwidth in IS-IS?

Medium
24

What are valid ways to configure IS-IS on a Junos interface? (Choose TWO)

Medium
25

Why would you set an interface to 'passive' in IS-IS?

Medium
26

An 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?

Hard
27

You observe that an IS-IS adjacency is stuck in 'Initializing'. What is the most likely cause?

Medium
28

What are the consequences of a mismatch in metric style (narrow vs wide) between IS-IS neighbors? (Choose THREE)

Hard
29

Which level is enabled by default in Junos when configuring IS-IS on an interface?

Easy
30

What is the default behavior when an IS-IS router receives an LSP it already has?

Medium
31

In a multi-access network, which PDU is responsible for the DIS election?

Medium
32

You are troubleshooting a DIS election issue on a broadcast segment. What is the tie-breaker if the DIS priorities are equal?

Hard
33

Which of the following are true regarding IS-IS Level 1/Level 2 routers? (Choose TWO)

Medium
34

Which of the following scenarios would prevent an IS-IS adjacency from forming? (Choose TWO)

Medium
35

Which TWO characteristics describe the behavior and properties of Level 1 and Level 2 routing in IS-IS? (Choose two)

Easy
36

Which of the following is a valid IS-IS PDU type?

Easy
37

How does an IS-IS router identify the DIS in its hello packets?

Hard
38

You 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?

Hard
39

Which of the following are valid ways to influence path selection in IS-IS? (Choose THREE)

Hard
40

Which of the following are true about CSNP and PSNP? (Choose THREE)

Hard
41

Which of the following is required for two routers to form a Level 2 adjacency?

Easy
42

When should you consider increasing the 'csnp-interval'?

Hard
43

Which command displays the IS-IS interface parameters?

Easy
44

Which of the following are valid IS-IS PDU types? (Choose THREE)

Medium
45

A 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?

Medium
46

What is the default IS-IS metric for an interface in Junos?

Easy
47

An 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)

Medium
48

When using authentication in IS-IS, where can you apply the password?

Hard
49

Which of the following are true about pseudonode LSPs? (Choose THREE)

Hard
50

You need to redistribute OSPF routes into IS-IS. Where do you configure this?

Hard
51

What is the function of the DIS in an IS-IS broadcast network?

Medium
52

An 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?

Medium
53

What is the purpose of the 'lsp-lifetime' command?

Hard
54

A 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?

Hard
55

Which of the following are true about IS-IS Level-1 and Level-2 areas? (Choose TWO)

Medium

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.
juniper-jncis-ent JUNIPER-JNCIS-ENT is is Practice Questions