Juniper JNCIS-ENT Sample Questions & Practice Test

JNCIS-ENT is a specialist enterprise route for candidates who work with Juniper routing, switching, OSPF, BGP, VLANs, policy, redundancy, and campus or branch troubleshooting.

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

What these questions test

• applying OSPF, BGP, VLAN, spanning-tree, and redundancy concepts to enterprise symptoms
• reading route-selection and policy behavior from operational evidence
• separating switching-layer problems from routing, addressing, and control-plane issues
• choosing safe troubleshooting actions rather than broad disruptive changes

Sample Exam Questions

Question 1

Topic: OSPF adjacency

Two routers on the same segment fail to become OSPF neighbors. What should be checked early?

• A. Area ID, hello/dead timers, authentication, subnet, MTU, and interface state
• B. Only the rack unit number
• C. Whether the hostname includes a vowel
• D. The number of unused switch ports

Best answer: A

Explanation: OSPF neighbor formation depends on matching and compatible parameters plus reachability. Area, timers, authentication, network type, MTU, and interface health are practical checks.

Question 2

Topic: BGP policy

A prefix is learned from a neighbor but not advertised to another neighbor. What is the most relevant check?

• A. Monitor brightness
• B. Applied import and export policies plus route eligibility
• C. Whether SNMP is disabled
• D. The length of the interface description

Best answer: B

Explanation: BGP advertisement is heavily policy-driven. Export policy, route eligibility, next-hop behavior, and neighbor state determine whether a route is advertised.

Question 3

Topic: VLANs

Users in one VLAN cannot reach their default gateway. Which evidence is most relevant first?

• A. User wallpaper settings
• B. Whether DNSSEC is enabled
• C. VLAN membership, trunking, interface state, gateway address, and ARP behavior
• D. The NTP server location only

Best answer: C

Explanation: VLAN access issues usually involve port membership, tagging/trunking, gateway addressing, physical state, or ARP. DNS and NTP are usually later checks.

Question 4

Topic: route preference

Two routes to the same prefix exist from different protocols. What helps determine which is installed?

• A. The number of users on the network
• B. Syslog message font
• C. Dashboard language
• D. Protocol preference and route attributes

Best answer: D

Explanation: Route selection considers Junos route preference and other attributes. Candidates should distinguish route availability from route selection.

Question 5

Topic: redundancy

Why use first-hop redundancy in an enterprise LAN?

• A. To provide gateway continuity if one device fails
• B. To remove all routing protocols
• C. To prevent all broadcast traffic
• D. To replace endpoint addressing

Best answer: A

Explanation: First-hop redundancy helps clients retain gateway service during device failure or maintenance. It does not eliminate routing or endpoint configuration needs.

Question 6

Topic: spanning tree

What problem is spanning tree intended to prevent?

• A. Duplicate DNS names
• B. Layer 2 loops in redundant switching topologies
• C. Weak user passwords
• D. Incorrect BGP communities

Best answer: B

Explanation: Spanning tree blocks redundant paths when needed to avoid loops. It is a switching control-plane mechanism, not a DNS, password, or BGP feature.

Question 7

Topic: high availability

Which change is safest before planned maintenance on a redundant path?

• A. Shut down every uplink at once
• B. Delete all policies
• C. Verify failover state and expected traffic path before removing a device
• D. Disable logging to reduce noise

Best answer: C

Explanation: Redundancy must be verified before maintenance. Confirming state and traffic path reduces surprise outages and supports rollback planning.

Question 8

Topic: traffic engineering

A branch should prefer a primary WAN link but fail over to backup. What should the design control?

• A. Interface description spelling only
• B. Number of saved CLI sessions
• C. Whether switch ports are named alphabetically
• D. Route preference, policy, or metrics so the desired path wins until failure

Best answer: D

Explanation: Path preference can be controlled through metrics, route preference, or policy depending on protocol and design. The goal is deterministic primary and backup behavior.

Question 9

Topic: prefix filtering

Why filter routing updates at the edge of an enterprise network?

• A. To prevent unwanted prefixes from being accepted or advertised
• B. To make all routes static
• C. To replace physical security
• D. To remove the need for monitoring

Best answer: A

Explanation: Prefix filters and route policies control route propagation and reduce mistakes. They do not eliminate the need for monitoring or other controls.

Question 10

Topic: multicast basics

What is a common multicast design concern?

• A. Making every VLAN untagged
• B. Ensuring multicast traffic reaches receivers without flooding everywhere unnecessarily
• C. Removing default gateways
• D. Replacing route policy with DNS

Best answer: B

Explanation: Multicast designs must balance delivery to receivers with control of unnecessary traffic. Candidates should recognize receiver, routing, and flooding behavior.

Question 11

Topic: troubleshooting

A routing change creates asymmetric paths and application problems. What should be reviewed?

• A. Browser bookmarks only
• B. The number of CLI windows open
• C. Forward and return paths, route policy, firewall state, and NAT dependencies
• D. Whether interface names use uppercase

Best answer: C

Explanation: Asymmetric routing can break stateful inspection, NAT, or application assumptions. Review both directions and policy behavior rather than only one route.

Question 12

Topic: enterprise design

What is a good reason to summarize routes?

• A. To delete all backup paths
• B. To disable convergence
• C. To make VLANs unnecessary
• D. To reduce routing-table size and hide internal detail where appropriate

Best answer: D

Explanation: Route summarization can improve scalability and reduce detail propagation. It must be designed carefully so reachability and troubleshooting remain predictable.

Quick readiness checklist

JNCIS-ENT practice update

Use this page to preview JNCIS-ENT sample questions and confirm the exam fit. If you want IT Mastery practice updates for this route, use the Notify me form above.