Juniper Networks · Free Practice Questions · Last reviewed May 2026
36real exam-style questions organised by domain, each with the correct answer highlighted and a plain-English explanation of why it's right — and why the others are wrong.
A network engineer needs to commit a configuration change but wants to ensure the change can be easily reverted if it causes issues. Which approach should the engineer take?
Use the 'commit and-quit' command to apply changes.
Use the 'commit confirmed' command with a timeout.
Commit confirmed provides automatic rollback if not confirmed.
Use the 'commit check' command before committing.
Use the 'rollback 0' command after committing.
An administrator wants to view the current operational status of interface ge-0/0/1 on a Junos device. Which command displays this information?
show interfaces terse ge-0/0/1
Shows operational status in concise format.
show configuration interfaces ge-0/0/1
monitor interface ge-0/0/1
show interface ge-0/0/1
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?
show route table inet.0
Displays IPv4 unicast route table.
show route table inet6.0
show route forwarding-table
show route protocol bgp
An engineer needs to apply a configuration change to the device, but only if the configuration is syntactically correct. Which command should be used before committing?
commit
commit check
Validates syntax without committing.
commit confirmed
show | compare
An administrator wants to navigate to the configuration mode to make changes to the device. Which command should be used?
set
edit
configure
Enters configuration mode.
cli
During troubleshooting, an engineer needs to view real-time logging messages on a Junos device. Which command should be used?
file show /var/log/messages
monitor start messages
Displays real-time log messages.
show log messages
traceoptions
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Practice this domainA network engineer is configuring a new Juniper device. They intend to apply a firewall filter to an interface to only allow SSH traffic from a specific management subnet. Which configuration approach best follows Juniper best practices?
Define the filter under 'firewall family inet' and apply it under 'interfaces ge-0/0/0 unit 0 family inet filter input filter-name'
This follows Juniper best practices for applying firewall filters.
Define the filter under 'firewall family inet' and apply it under 'interfaces lo0 unit 0 family inet filter input filter-name'
Define the filter under 'firewall family inet' and apply it under 'interfaces ge-0/0/0 unit 0 family inet input'
Define the filter under 'firewall family any' and apply it under 'interfaces ge-0/0/0 unit 0 family any filter input'
A junior engineer is asked to change the hostname of a Juniper device from 'Router-1' to 'Core-Router'. Which command sequence correctly commits the change?
set system host-name Core-Router; commit
Correct syntax.
edit system; set host-name Core-Router; commit
set system hostname Core-Router; commit
set system host-name Core-Router; commit
During troubleshooting, an engineer notices that BGP sessions are flapping. They suspect that the issue might be related to the maximum number of routes allowed. To see if the BGP import policy is rejecting routes, which operational command would provide immediate insight?
show version
show interfaces terse
show route protocol bgp
show bgp neighbor x.x.x.x
Displays BGP neighbor details including prefix counts and policy statistics.
When configuring a new Juniper router, an engineer needs to ensure that configuration changes are not automatically committed after a certain time if not explicitly confirmed. Which configuration parameter controls this?
commit check
commit at
commit synchronize
commit confirmed
Requires confirmation; otherwise rolled back after timeout.
A network administrator wants to view the current candidate configuration that has not yet been committed. Which command should be used?
show configuration | display set
show configuration
Shows the candidate configuration.
show configuration | compare rollback 0
show interface terse
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?
Use a firewall filter that permits all management traffic at the top of the list on each interface
Apply a firewall filter on the loopback interface (lo0) to protect the device
Best practice: use loopback filter to control access to the device itself.
Apply a firewall filter to the management interface (fxp0)
Disable the firewall filter on all interfaces
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Practice this domainA network engineer notices that a device is not sending SNMP traps to the NMS. Which operational command should be used to verify SNMP configuration?
show system uptime
show route
show snmp
Displays SNMP configuration and trap settings.
show interfaces terse
A network administrator is troubleshooting high CPU usage on a Juniper router. Which command helps identify which process is consuming the most CPU?
show log messages
show system memory
show system processes extensive
Displays detailed process CPU usage.
show interfaces
After a software upgrade, BGP sessions are not establishing. The engineer runs 'show bgp summary' and sees that all sessions are in Idle state. What is the most likely cause?
The BGP group configuration is missing
Without proper configuration, BGP cannot start.
The interface is administratively down
The router has a full BGP table
The firewall filter is blocking ICMP
A junior engineer needs to collect a snapshot of the current system state, including routing tables, interfaces, and configuration, for a support ticket. Which command achieves this?
show configuration
show interfaces
request support information
Gathers comprehensive system data for troubleshooting.
show route
A network engineer wants to schedule a reboot of a Juniper device at 3:00 AM. Which command should be used?
request system configuration rescue save
request system reboot
request system reboot at 03:00
Schedules reboot at specified time.
load override /config/juniper.conf.gz
A router is experiencing intermittent packet loss. The engineer runs 'show interfaces ge-0/0/0 extensive' and notices a high number of input errors but no output errors. What is the most likely cause?
The cable is too long
A faulty transceiver
Faulty optics can cause input errors.
MTU mismatch
The interface is oversubscribed
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Practice this domainA network engineer is troubleshooting a connectivity issue and wants to see the active routes in the routing table. Which Junos CLI command should they use?
show log messages
show configuration
show interface
show route
Displays the routing table.
An organization has two ISPs and wants to load-balance traffic equally across both links for all outbound traffic. Which routing configuration approach should be used?
Configure two static default routes with different metric values.
Configure policy-based routing to match all traffic and forward to both ISPs.
Configure two static default routes with equal metric values and enable ECMP.
ECMP allows load balancing across equal-cost routes.
Establish BGP sessions with both ISPs and rely on BGP path selection.
During a routing table lookup, a packet matches both a static route and an OSPF route to the same destination. Which route will be installed in the forwarding table?
Both routes, if they are equal-cost.
The route with the higher preference value.
The OSPF route, because OSPF is a dynamic routing protocol.
The static route, because it has a lower preference value.
Static route preference 5 is lower than OSPF's 10.
Which TWO statements about active routes in the Junos routing table are correct?
All routes in the routing table are active.
Multiple active routes can exist for the same prefix.
An active route is installed in the forwarding table.
Active routes are used for forwarding.
An active route must have a valid next hop.
Without a valid next hop, the route cannot be active.
An active route is always preferred over a passive route.
Which THREE statements about static routes in Junos are correct?
Static routes have a default preference of 5.
Default preference for static routes is 5.
You can configure multiple static routes to the same destination for load balancing.
Multiple static routes with equal metrics enable ECMP.
The preference of a static route cannot be changed.
Static routes automatically update if the next hop becomes unreachable.
A static route can use a qualified next hop to specify a fallback.
Qualified next hop allows a backup route.
Which THREE route types are considered protocol-independent in Junos?
BGP routes
Direct routes
Direct routes are protocol-independent, derived from interface configuration.
Local routes
Local routes are protocol-independent.
Static routes
Static routes are configured manually, protocol-independent.
OSPF routes
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Practice this domainA network administrator notices that traffic between two VLANs is not reaching its destination. The switch has an IRB interface configured with an IP address in each VLAN's subnet. What is the most likely missing configuration?
The IRB interface does not have an IP address configured.
The VLANs are on different switches.
The VLANs are not defined on the switch.
Without defining the VLANs, the switch cannot associate ports or IRB interfaces with them.
The switch ports are not configured for VLAN tagging.
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?
The MTU on the interface is mismatched.
A mismatch in MTU can prevent OSPF from exchanging DD packets, causing the adjacency to remain in EXSTART.
The router IDs are not the same.
The area ID is not configured.
The hello and dead intervals are mismatched.
An administrator needs to ensure that traffic from the 192.168.1.0/24 subnet is allowed to reach the internet through a Juniper SRX firewall. The SRX is configured with security policies. Which policy element is required to permit this traffic?
Source address
Application
Destination zone
Source zone
A security policy must specify a source zone to match incoming traffic.
A network engineer is designing a redundant network with two Juniper routers running VRRP. The virtual IP address is 10.0.0.1. Both routers are configured as VRRP group 1. What is the purpose of the 'priority' parameter in VRRP configuration?
It sets the interval for VRRP advertisements.
It determines the master router election.
Higher priority increases the chance of becoming the master.
It determines the virtual MAC address.
It changes the virtual IP address.
Which TWO statements about Juniper's implementation of static routes are correct? (Choose two.)
The default preference for static routes is 5.
Junos assigns a default preference of 5 to static routes.
Static routes always have a metric of 1.
Static routes are automatically redistributed into OSPF.
Static routes can have a next-hop of 'discard'.
The 'discard' next-hop (null0) is a valid next-hop for static routes to drop traffic.
The default preference for static routes is 170.
You are responsible for a Juniper MX router that connects two customer sites over a Layer 3 VPN. The router is configured with BGP for VPN routes and uses MPLS to forward traffic. Recently, the customer reported that traffic from Site A (10.0.1.0/24) to Site B (10.0.2.0/24) is intermittently failing. You check the routing table on the router and see that both routes are present with valid next-hops. However, when you ping from the router's loopback to the remote site's loopback, the ping succeeds. MPLS labels are being assigned and the LSP is up. You also notice that when the failure occurs, the router's BGP session to the remote PE is still established. The failure seems random and lasts a few seconds before recovering. Which troubleshooting step is most likely to identify the root cause?
Check the interface error counters for CRC errors or drops.
Review the forwarding table for the affected prefixes and check for any discrepancies.
The forwarding table may have stale entries or incorrect label operations causing intermittent forwarding failures.
Verify the BGP session state and check for route flapping.
Check the MPLS label switching table to ensure labels are correctly assigned.
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Practice this domainA network engineer is configuring a new Juniper device and needs to ensure that the configuration is saved persistently across reboots. Which command should be used?
save
request system reboot
show configuration
commit
Commits the candidate configuration to the active configuration, ensuring persistence across reboots.
An administrator needs to quickly revert all uncommitted configuration changes and return the device to the last committed configuration. Which command accomplishes this?
rollback 0
Reverts the candidate configuration to the last committed configuration.
delete configuration
load override
rollback 1
A Juniper device is experiencing high CPU utilization due to a routing protocol process. The engineer suspects a specific BGP peer is causing the issue. Which operational command can be used to collect diagnostic information about the routing protocol processes?
show system processes extensive
Provides detailed process-level CPU and memory statistics, useful for diagnosing high CPU.
request support information
show bgp summary
monitor traffic interface
A junior engineer is troubleshooting connectivity issues and wants to trace the path packets take to a remote destination. Which Junos command should be used?
monitor traffic
show route
traceroute
Displays the route packets take to a destination, hop by hop.
ping
An engineer needs to view the current active configuration on a Juniper device. Which command will display the configuration that is currently running?
show chassis hardware
show interfaces terse
show configuration
Displays the current active configuration (or candidate if uncommitted changes exist).
show system commit
A network administrator is configuring a new interface and wants to ensure that the interface is enabled and can pass traffic. Which configuration element is required?
set interfaces ge-0/0/0 enable
set interfaces ge-0/0/0 unit 0 family inet address 192.168.1.1/24
Configuring an IP address on the interface implicitly enables it.
set interfaces ge-0/0/0 unit 0 family inet
set interfaces ge-0/0/0 disable
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Practice this domainThe JNCIA-JUNOS exam has 65 questions and must be completed in 90 minutes. The passing score is 700/1000.
Scenario-based questions covering exam objectives with detailed answer explanations.
The exam covers 6 domains: User Interfaces, Junos Configuration Basics, Operational Monitoring and Maintenance, Routing Fundamentals, Networking Fundamentals, Junos OS Fundamentals. Questions are weighted by domain — higher-weight domains appear more on your actual exam.
No. These are original exam-style practice questions written against the official Juniper Networks JNCIA-JUNOS exam objectives. They are not copied from the real exam. Courseiva focuses on genuine understanding, not memorisation of braindumps.
Courseiva tracks your accuracy per domain and routes you toward weak areas automatically. Free, no account required.