Juniper JNCIA-Junos Sample Questions & Practice Test

JNCIA-Junos is an associate Juniper route for candidates who need Junos OS fundamentals, CLI workflow, interface configuration, routing basics, operational monitoring, and troubleshooting judgment.

Use this page to try original IT Mastery sample questions on Junos decisions. They are not official Juniper exam questions.

What these questions test

• navigating Junos operational and configuration modes without confusing commit behavior
• identifying interface, routing, and monitoring commands from realistic symptoms
• distinguishing static routing, dynamic routing concepts, and forwarding behavior
• reading configuration intent instead of memorizing isolated command fragments

Sample Exam Questions

Question 1

Topic: Junos CLI modes

An engineer needs to view interface status without changing the configuration. Which CLI mode is most appropriate?

• A. Configuration mode only
• B. Operational mode
• C. Rescue mode
• D. Commit confirmed mode

Best answer: B

Explanation: Operational mode is used for show, monitor, ping, traceroute, and other operational commands. Configuration mode is used to change candidate configuration before commit.

Question 2

Topic: commit workflow

Why is the Junos candidate configuration important?

• A. It lets changes be staged and reviewed before they become active
• B. It disables rollback
• C. It makes every command permanent immediately
• D. It removes the need for syntax checks

Best answer: A

Explanation: Junos uses a candidate configuration. Changes are made in the candidate, checked, and then committed to become active, which supports review and rollback discipline.

Question 3

Topic: rollback

A recent configuration change caused loss of reachability. Which feature helps restore a prior known configuration?

• A. Increasing the MTU randomly
• B. Renaming the router
• C. Rollback
• D. Disabling all interfaces

Best answer: C

Explanation: Junos keeps prior configurations that can be rolled back and committed. This is safer than guessing at unrelated interface or routing changes.

Question 4

Topic: interface troubleshooting

An interface is administratively disabled. Which type of evidence should be reviewed first?

• A. Weather forecast
• B. DNS zone serial number
• C. User browser cache
• D. Show interface status and configuration state

Best answer: D

Explanation: Interface troubleshooting starts with operational state and configuration. An admin-down state usually points to configuration rather than physical media alone.

Question 5

Topic: routing table

What does the routing table primarily determine?

• A. Which next hop is selected for a destination prefix
• B. Which user gets administrator access
• C. Whether SSH passwords are complex
• D. Which syslog server stores logs

Best answer: A

Explanation: The routing table contains routes and next-hop information used for forwarding decisions. It is separate from authentication, logging, or password policy.

Question 6

Topic: static routes

When is a static route often appropriate?

• A. To automatically discover every network change
• B. For a simple, stable path where dynamic routing is unnecessary
• C. To replace interface addressing
• D. To encrypt all traffic

Best answer: B

Explanation: Static routes fit simple, predictable paths. Dynamic protocols are better when topology changes and route exchange need to happen automatically.

Question 7

Topic: OSPF basics

What is OSPF designed to do?

• A. Store device backups
• B. Replace VLAN tagging
• C. Exchange link-state routing information inside an administrative domain
• D. Manage endpoint antivirus

Best answer: C

Explanation: OSPF is an interior gateway protocol that exchanges link-state information and computes paths. It does not handle backups, VLAN tagging, or endpoint security.

Question 8

Topic: monitoring

A router has intermittent packet loss. Which evidence is most useful early?

• A. The color of the rack label
• B. Only the hostname length
• C. Whether users like the network name
• D. Interface counters, logs, routing state, and path tests

Best answer: D

Explanation: Packet loss troubleshooting needs operational evidence. Interface errors, logs, routing behavior, ping, and traceroute help narrow physical, forwarding, or path issues.

Question 9

Topic: rescue configuration

What is the purpose of a rescue configuration?

• A. A known-good configuration that can help recover device access
• B. A temporary screen theme
• C. A replacement for all backups
• D. A command that deletes inactive interfaces

Best answer: A

Explanation: A rescue configuration is a saved known-good configuration used for recovery. It should not be treated as the only backup or as a substitute for change control.

Question 10

Topic: configuration hierarchy

Why does Junos configuration hierarchy matter?

• A. It prevents routing protocols from running
• B. It organizes related settings so context affects where commands apply
• C. It hides all interface settings
• D. It replaces monitoring commands

Best answer: B

Explanation: Junos configuration is hierarchical. Candidates need to understand context so they edit the correct part of the configuration tree.

Question 11

Topic: security access

Which practice supports safer device administration?

• A. Share one root password with every user
• B. Permit management from the entire internet by default
• C. Assign administrator access based on role and use secure management paths
• D. Disable audit logs

Best answer: C

Explanation: Secure management uses least privilege, controlled access paths, and logging. Shared credentials and broad management exposure increase operational risk.

Question 12

Topic: troubleshooting sequence

What is the best first approach when a Junos device stops forwarding traffic after a change?

• A. Guess a new routing protocol
• B. Replace every cable without checking counters
• C. Delete all static routes
• D. Compare recent changes, logs, interface state, routing state, and commit history

Best answer: D

Explanation: Troubleshooting should start with evidence and the change window. Commit history, logs, interface status, and routing state help isolate the most likely cause.

Quick readiness checklist

JNCIA-Junos practice update

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