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Hard Difficulty Questions

Practise Juniper Networks Certified Associate Junos JNCIA-Junos practice questions — original exam-style scenarios covering every exam domain, with detailed explanations, wrong-answer analysis, and common exam traps.

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JNCIA-JUNOS
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Juniper Networks
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Scenario guide

How to approach hard difficulty questions

These are the questions most candidates get wrong. They require connecting multiple concepts, reading tricky output, or knowing edge-case behaviour that isn't on most study cards. Practising them trains you to operate under uncertainty — a necessary skill on the real exam.

Quick answer

Hard Difficulty Questions 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.

Related practice questions

Related JNCIA-JUNOS topic practice pages

Scenario questions usually connect to one or more exam topics. Use these links to review the underlying concepts behind the scenario.

User Interfaces practice questions

Practise JNCIA-JUNOS questions linked to User Interfaces.

Junos Configuration Basics practice questions

Practise JNCIA-JUNOS questions linked to Junos Configuration Basics.

Operational Monitoring and Maintenance practice questions

Practise JNCIA-JUNOS questions linked to Operational Monitoring and Maintenance.

Routing Fundamentals practice questions

Practise JNCIA-JUNOS questions linked to Routing Fundamentals.

Networking Fundamentals practice questions

Practise JNCIA-JUNOS questions linked to Networking Fundamentals.

Junos OS Fundamentals practice questions

Practise JNCIA-JUNOS questions linked to Junos OS Fundamentals.

JNCIA-JUNOS fundamentals practice questions

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JNCIA-JUNOS scenario practice questions

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JNCIA-JUNOS troubleshooting practice questions

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Practice set

Practice scenarios

Question 1hardmultiple choice
Review the full routing breakdown →

You are the network engineer for a mid-sized enterprise with a Juniper MX router running Junos. The router has two uplinks to the internet: one to ISP-A via ge-0/0/0 (10.0.0.1/30) and one to ISP-B via ge-0/0/1 (10.0.0.5/30). You have configured static default routes to both ISPs: one to 10.0.0.2 and one to 10.0.0.6. Both routes have the same preference (default 5) and metric. You enabled ECMP to load-balance outbound traffic. After testing, you notice that all traffic is being sent only to ISP-A, and none to ISP-B. You verify that both interfaces are up and that the next-hop addresses are reachable. You check the routing table and see both routes are active but with different next-hop counts. What is the most likely cause of the traffic not being load-balanced?

Question 2hardmulti select
Full question →

Which TWO statements correctly describe the behavior of the 'commit confirmed' command in Junos?

Question 3hardmulti select
Full question →

Which TWO statements correctly describe Junos configuration hierarchy and management?

Question 4hardmultiple choice
Review the full OSPF breakdown →

Your company operates a dual-homed network with two Juniper MX routers (R1 and R2) each connected to a different ISP. R1 uses BGP to receive a default route from ISP-A (preference 170), and R2 uses BGP to receive a default route from ISP-B (preference 170). Additionally, both routers have a static default route pointing to a local next-hop (192.0.2.1) with preference 5 for backup. R1 and R2 are connected via an internal link (10.0.0.0/30) and run OSPF to exchange internal routes. You notice that traffic from internal hosts is always exiting via R1's ISP-A link, even when R1's BGP session to ISP-A goes down. The OSPF routes are preferred. You want traffic to fail over to R2's ISP-B link when R1 loses its BGP default. Which configuration change should you make?

Question 5hardmulti select
Full question →

Which THREE statements are true about commit operations in Junos OS?

Question 6hardmultiple choice
Open the full VLAN trunking answer →

An engineer is designing a network with two routers connected via a serial link. The link should support multiple logical subinterfaces for different VLANs. Which encapsulation type must be used on the serial interface?

Question 7hardmultiple choice
Study the full IPv6 explanation →

Refer to the exhibit. An engineer configures a new IPv6 address on ge-0/0/0 unit 0 by entering the following commands in configuration mode:

set interfaces ge-0/0/0 unit 0 family inet6 address 2001:db8::2/64 commit

After the commit, the engineer runs 'show interfaces terse ge-0/0/0' and sees only the two original addresses. What is the most likely cause?

Exhibit

Refer to the exhibit.

user@router> show configuration interfaces ge-0/0/0
unit 0 {
    family inet {
        address 10.0.0.1/24;
    }
    family inet6 {
        address 2001:db8::1/64;
    }
}

user@router> show interfaces terse ge-0/0/0
Interface               Admin Link Proto    Local                 Remote
ge-0/0/0                up    up   inet     10.0.0.1/24
                                   inet6    2001:db8::1/64
Question 8hardmultiple choice
Review the full OSPF breakdown →

You are a junior network engineer at a company that uses Juniper MX routers. You are troubleshooting a connectivity issue on a branch router. The branch router has two upstream links to the corporate network: ge-0/0/0 (10.1.1.1/30, connected to core router A) and ge-0/0/1 (10.1.1.5/30, connected to core router B). The branch router runs OSPF and has a default route learned from both upstream routers. The routing table shows two equal-cost default routes via both next hops. However, traffic from the branch to the corporate network is experiencing intermittent high latency and some packet loss. You suspect that asymmetric routing is causing issues because the return traffic is not following the same path. You want to influence the router to prefer one upstream link for all traffic to the corporate network. You have decided to adjust the OSPF metric on the branch router to make the link to core router A more preferred. You are in configuration mode on the branch router. Which single configuration change will accomplish this goal?

Question 9hardmultiple choice
Full question →

Refer to the exhibit. A network engineer sees repeated 'PFE interrupt error' messages in the log for fpc0. What is the most likely impact and recommended action?

Exhibit

Refer to the exhibit.

user@router> show log messages | match "fpc0"
Dec 10 14:22:01 router fpc0 MCSCHED: PFE interrupt error, restarting...
Dec 10 14:22:05 router fpc0 MCSCHED: PFE interrupt error, restarting...
Dec 10 14:22:09 router fpc0 MCSCHED: PFE interrupt error, restarting...
Dec 10 14:22:13 router fpc0 MCSCHED: PFE interrupt error, restarting...
Dec 10 14:22:17 router fpc0 MCSCHED: PFE interrupt error, restarting...
Question 10hardmultiple choice
Full question →

During a maintenance window, an engineer needs to apply a series of configuration changes that are stored in a text file. Which command sequence should be used to load and apply the changes from the file?

Question 11hardmulti select
Review the full routing breakdown →

Which TWO statements about Juniper's implementation of static routes are correct? (Choose two.)

Question 12hardmultiple choice
Review the full OSPF breakdown →

A network engineer is troubleshooting OSPF adjacencies between two Juniper routers. The routers are directly connected and have matching OSPF configurations except for the router IDs. Router A has router-id 10.0.0.1, Router B has router-id 10.0.0.2. The adjacency remains in the EXSTART state. What is the most likely cause?

Question 13hardmulti select
Full question →

Which THREE of the following statements are true regarding Junos OS commit operations?

Question 14hardmulti select
Full question →

Which THREE commands are valid Junos operational mode commands for monitoring network diagnostics? (Choose three.)

Question 15hardmultiple choice
Full question →

During troubleshooting, an engineer needs to view real-time logging messages on a Junos device. Which command should be used?

Question 16hardmultiple choice
Review the full routing breakdown →

A junior engineer is troubleshooting a routing issue and wants to see the route table for IPv4 unicast routes. Which command will display this information?

Question 17hardmultiple choice
Full question →

Refer to the exhibit. An engineer runs the command but sees no output. What is the most likely reason?

Exhibit

user@router> show configuration | display set | match "ge-0/0/0"
set interfaces ge-0/0/0 unit 0 family inet address 10.0.0.1/24
Question 18hardmulti select
Full question →

Which THREE are valid methods to exit configuration mode in Junos? (Choose three.)

Question 19hardmultiple choice
Read the full network assurance explanation →

An engineer is designing a network and needs to ensure that management traffic (SSH, SNMP) is always permitted, even if an interface firewall filter is applied. Which Juniper best practice should be followed?

Question 20hardmulti select
Review the full routing breakdown →

Which THREE commands are used for operational monitoring of routing protocols?

These JNCIA-JUNOS practice questions are part of Courseiva's free Juniper Networks certification practice question bank. Courseiva provides original exam-style JNCIA-JUNOS questions with detailed explanations, topic-based practice, mock exams, readiness tracking, and study analytics.