JNCIA-JUNOS User Interfaces — All Questions With Answers

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?

Question 2easymultiple choice

An administrator wants to view the current operational status of interface ge-0/0/1 on a Junos device. Which command displays this information?

Question 3hardmultiple choice

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 4mediummultiple choice

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?

Question 5easymultiple choice

An administrator wants to navigate to the configuration mode to make changes to the device. Which command should be used?

Question 6hardmultiple choice

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

Question 7mediummultiple choice

A network engineer needs to revert to the configuration that was active before the last commit. Which command accomplishes this?

Question 8easymultiple choice

An administrator wants to see the differences between the candidate configuration and the active configuration. Which command should be used?

Question 9mediummulti select

Which TWO statements are true regarding the Junos CLI? (Choose two.)

Question 10hardmulti select

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

Question 11easymulti select

Which TWO commands can be used to view the current operational state of an interface? (Choose two.)

Question 12mediummultiple choice

Refer to the exhibit. Based on the output, what is the operational status of interface ge-0/0/0?

Exhibit

show interfaces terse ge-0/0/0
Interface    Admin Link Proto    Local                 Remote
ge-0/0/0     up    up   inet     192.168.1.1/24

Question 13hardmultiple choice

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 14hardmultiple choice

Open the full VLAN trunking answer →

You are a network engineer for a service provider that recently deployed a Juniper MX router at a new Point of Presence (PoP). The router is used to aggregate customer connections and exchange routes with upstream providers via BGP. After the initial configuration, you notice that the router is not learning any routes from one of the upstream BGP peers. You have verified that the BGP session is established (state Established) and that the peer is sending routes. You suspect that the issue might be related to the firewall filter or routing policy. You want to determine if any inbound routes are being rejected and why. Which command would provide the most direct information about why routes are being rejected?

Question 15mediummultiple choice

You are managing a Juniper EX4300 switch that serves as a Layer 3 access switch for a campus network. The switch has multiple VLANs configured with IRB interfaces. Users in VLAN 10 report that they cannot reach the default gateway (IRB.10) even though other VLANs are working fine. You check the configuration and see that interface irb.10 is configured with an IP address. You also verify that the VLAN is associated with the correct access ports. However, when you ping the IRB.10 address from the switch itself, it fails. You suspect that the issue might be that the IRB interface is not 'up'. Which command would you use to quickly verify the operational status of the IRB interface?

Question 16mediummultiple choice

A network engineer needs to view the operational status of all interfaces on a Junos device, including those that are disabled. Which command should be used?

Question 17hardmulti select

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

Question 18easymultiple choice

Refer to the exhibit. Which interface has an operational issue that prevents it from passing traffic?

Exhibit

Refer to the exhibit.

user@router> show interfaces terse
Interface       Admin Link Proto    Local                 Remote
ge-0/0/0        up    up   inet     10.1.1.1/24
ge-0/0/1        up    down inet     10.1.2.1/24
ge-0/0/2        down  down
lo0             up    up   inet     192.168.1.1/32
                                   inet6    fe80::1/128

Question 19mediummultiple choice

You are a network engineer for a company that has just deployed a Juniper SRX firewall in a branch office. The device has multiple interfaces: ge-0/0/0 connected to the internet, ge-0/0/1 connected to the internal LAN (192.168.1.0/24), and ge-0/0/2 connected to a DMZ (10.0.0.0/24). After initial configuration, you attempt to ping from the SRX to a server on the internet (8.8.8.8) but receive no response. You also notice that internal users can access the internet. You have verified the routing table shows a default route via ge-0/0/0. The security policies appear correct. You suspect the issue is related to interface configuration. What is the most likely cause and the correct course of action?

Question 20mediummulti select

Study the full IPv6 explanation →

Which TWO statements correctly describe the behavior of the Junos CLI operational mode?

Question 21hardmultiple choice

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 22hardmultiple 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 23mediumdrag order

Arrange the steps to configure a static route in Junos OS in the correct order.

Drag steps to the numbered slots on the right, or tap a step then tap a slot.

Steps

Order

1Step 1

2Step 2

3Step 3

4Step 4

5Step 5

Question 24mediumdrag order

Arrange the steps to perform a system backup (snapshot) on a Junos device.

Drag steps to the numbered slots on the right, or tap a step then tap a slot.

Steps

Order

1Step 1

2Step 2

3Step 3

4Step 4

5Step 5

Question 25mediummatching

Match each Junos CLI operational mode command to its function.

Drag a concept onto its matching description — or click a concept then click the description.

Concepts

Matches

Displays brief interface status and configuration

Displays the routing table

Displays the current active configuration

Displays system log messages

Captures and displays live traffic on an interface

Question 26mediummatching

Match each Junos interface type to its typical use.

Drag a concept onto its matching description — or click a concept then click the description.

Concepts

Matches

Out-of-band management interface

Gigabit Ethernet data interface

Loopback interface for router ID and management

Embedded management interface on some platforms

Generic routing encapsulation (GRE) tunnel

Question 27easymultiple choice

A network administrator wants to quickly review only the parts of the Junos configuration that differ from the factory defaults, to identify custom settings. Which command is most appropriate?

Question 28mediummultiple choice

A technician is troubleshooting a routing issue and needs to see real-time updates of BGP prefixes being received. Which command should be used?

Question 29hardmultiple choice

During a maintenance window, an engineer needs to apply a configuration change that reverts automatically if the commit fails or the administrator does not confirm within a set time. Which feature should be used?

Question 30easymultiple choice

A junior admin wants to see all commands available in operational mode that start with 'show'. What keystrokes should they use?

Question 31mediummultiple choice

An engineer is configuring a firewall filter and wants to verify the syntax of the configuration before committing. Which command should be used?

Question 32hardmultiple choice

After upgrading Junos, a router fails to boot with a file system error. The admin needs to recover the system from the backup partition. Which key should be pressed during boot to access the boot menu?

Question 33easymultiple choice

A user wants to ensure that a configuration change is applied across both Routing Engines in a dual-RE system. Which command must be used?

Question 34mediummultiple choice

An administrator needs to see which interfaces are configured and their current operational status in a concise format. Which command provides this information?

Question 35hardmultiple choice

A network operator is using the 'monitor traffic' command but wants to stop after capturing 100 packets. Which option should be added?

Question 36mediummulti select

An engineer needs to view the current operational state of the device, including system uptime, CPU load, and memory usage. Which two commands would provide this information? (Choose two.)

Question 37hardmulti select

A junior administrator is learning to navigate the Junos CLI. Which three statements about CLI modes are correct? (Choose three.)

Question 38easymulti select

Which THREE statements about the Junos CLI help system are correct? (Choose three.)

Question 39mediummultiple choice

Refer to the exhibit. An administrator sees the following configuration output. What is the purpose of the 'description' statement in this context?

Exhibit

interfaces {
    ge-0/0/0 {
        description "Link to Core-1";
        unit 0 {
            family inet {
                address 10.0.0.1/30;
            }
        }
    }
}

Question 40mediummultiple choice

Refer to the exhibit. An engineer notices high error counts on the interface. Based on the output, what is the most likely cause?

Exhibit

Physical interface: ge-0/0/0, Enabled, Physical link is Up
  Interface index: 145, SNMP ifIndex: 511
  Link-level type: Ethernet, MTU: 1514, Speed: 1Gbps
  Device flags   : Present Running
  Interface flags: SNMP-Traps Internal: 0x4000
  Link type      : Full-Duplex
  Link flags     : None
  Input errors:
    Errors: 0, Drops: 0, Framing errors: 0, Runts: 0, Giants: 0, Policed discards: 0, Resource errors: 0
  Output errors:
    Errors: 0, Drops: 0, Carrier transitions: 0, Collisions: 2546, Late collisions: 34, Deferred: 0, ...

Question 41mediummultiple choice

Refer to the exhibit. An administrator needs to ensure that all emergency (emerg) messages are logged to the console. Based on the configuration shown, which statement is correct?

Exhibit

system {
    syslog {
        console {
            any warning;
        }
        file messages {
            any any;
        }
        host 192.168.1.1 {
            any critical;
        }
    }
}

Question 42easymultiple choice

An engineer needs to view the current active configuration of a Junos device without making any changes. Which CLI mode should they use?

Question 43mediummultiple choice

A network administrator has made several configuration changes and now wants to revert all uncommitted changes back to the last committed configuration. Which command should they use?

Question 44hardmultiple choice

An engineer wants to apply a candidate configuration and automatically revert to the previous configuration after 10 minutes if the commit is not confirmed. Which command should be used?

Question 45easymultiple choice

A technician needs to display the contents of a configuration file stored on the device's hard disk. Which operational mode command should they use?

Question 46mediummultiple choice

An administrator is in configuration mode and wants to see only the interfaces configuration block while editing. Which command will display just that section?

Question 47mediummultiple choice

A junior engineer accidentally enters 'set interfaces ge-0/0/0 unit 0 family inet address 192.0.2.1/24' in operational mode. What will happen?

Question 48hardmultiple choice

An engineer needs to check if a junos configuration file is syntactically correct before applying it. Which command should be used?

Question 49easymultiple choice

A network engineer wants to see all commands entered in the current session. Which operational mode command should they use?

Question 50mediummultiple choice

An administrator is troubleshooting an interface and wants to see real-time packet statistics. Which command should they use?

Question 51mediummulti select

Which TWO commands can be used to view the current active configuration on a Junos device? (Choose two.)

Question 52hardmulti select

Which TWO statements are true about the 'commit confirmed' command? (Choose two.)

Question 53easymulti select

Which THREE modes can be used to enter configuration mode in Junos? (Choose three.)

Question 54mediummultiple choice

Refer to the exhibit. An engineer sees that the interface ge-0/0/0 has 'Admin up' and 'Link up'. What does this indicate?

Exhibit

show interfaces terse ge-0/0/0
Interface               Admin Link Proto    Local                 Remote
ge-0/0/0                up    up   inet     192.168.1.1/24
                                   inet6    fe80::1/64

Question 55hardmultiple choice

Refer to the exhibit. An engineer runs the command shown. What does this output indicate?

Exhibit

user@router# show | compare rollback 0
[edit interfaces ge-0/0/0 unit 0 family inet]
+      address 192.0.2.1/24;
-      address 10.0.0.1/24;

Question 56easymultiple choice

Refer to the exhibit. An engineer wants to revert to the configuration from January 14. Which rollback number should they use?

Exhibit

user@router> show system commit
0   2023-01-15 12:34:56 UTC by admin via cli
1   2023-01-14 09:15:00 UTC by admin via cli
2   2023-01-13 16:45:23 UTC by admin via cli

Question 57easymultiple choice

A network administrator needs to view the current configuration but is only interested in the interfaces section. Which CLI command should they use?

Question 58mediummultiple choice

An engineer is troubleshooting a connectivity issue and wants to see real-time interface traffic statistics. Which command provides continuous updates?

Question 59hardmultiple choice

A junior admin tries to commit a configuration but receives a 'commit error: syntax error' message. They suspect a missing closing brace. Which CLI command helps identify the exact line with the error?

Question 60mediummultiple choice

A network administrator accidentally deleted a vital part of the configuration while in configuration mode. They need to revert to the previous configuration without losing recent changes that are correct. Which action should they take?

Question 61easymultiple choice

A technician wants to view the system log messages in real time. Which command should they use?

Question 62hardmultiple choice

An operator needs to copy the running configuration to a remote FTP server for backup. Which command accomplishes this?

Question 63mediummultiple choice

A network engineer is in configuration mode and wants to see the configuration in a format that can be directly pasted into another router to reproduce the configuration. Which output modifier should they use?

Question 64hardmultiple choice

During a maintenance window, a network engineer is about to commit changes but wants to ensure no active sessions are disrupted. Which command should they run first?

Question 65easymultiple choice

A user wants to see all available commands starting with 'show'. Which key should they press after typing 'show'?

Question 66mediummulti select

Which TWO statements about the 'commit' operation in Junos OS are correct?

Question 67hardmulti select

Which THREE CLI features are available in Junos OS to assist with command entry?

Question 68mediummulti select

Which TWO commands can be used to view the current running configuration?

Question 69mediummultiple choice

Refer to the exhibit. What is the purpose of the 'unit 0' statement?

Exhibit

interfaces {
    ge-0/0/0 {
        unit 0 {
            family inet {
                address 10.0.0.1/24;
            }
        }
    }
}

Question 70hardmultiple choice

Refer to the exhibit. What does this output indicate?

Exhibit

user@router# show configuration | compare 
[edit interfaces]
+   ge-0/0/0 {
+       unit 0 {
+           family inet {
+               address 10.0.0.2/24;
+           }
+       }
+   }
-   ge-0/0/0 {
-       unit 0 {
-           family inet {
-               address 10.0.0.1/24;
-           }
-       }
-   }

Question 71easymultiple choice

Refer to the exhibit. What does this command accomplish?

Exhibit

user@router> help syslog messages | match error

KERNEL_ERROR    Kernel error messages
USER_ERROR      User-level error messages
DAEMON_ERROR    Daemon error messages

Question 72easymultiple choice

A junior engineer uses 'set system host-name R1' in configuration mode and exits without committing. After a reboot, the hostname reverts to the original. What step did the engineer miss?

Question 73hardmultiple choice

An engineer wants to see the differences between the active configuration and the candidate configuration. Which command should they use?

Question 74mediummultiple choice

While in configuration mode, an engineer types 'show' and sees a different output than when typing 'run show configuration'. Why?

Question 75easymultiple choice

A network engineer needs to revert to the configuration that was committed two commits ago. Which rollback number should they use?

Question 76mediummultiple choice

A user wants to discard all uncommitted changes and return to the last committed configuration without exiting configuration mode. Which command should they use?

Question 77easymultiple choice

During a maintenance window, an engineer makes critical changes and wants the configuration to automatically revert if they lose connectivity. Which command should they use before committing?

Question 78hardmultiple choice

What permission bit must be included in a custom login class to allow a user to execute the ping command?

Question 79hardmultiple choice

An engineer needs to apply a configuration change to all interfaces except the management interface (fxp0). Which approach is most efficient?

Question 80mediummultiple choice

An engineer wants to view system log messages as they are generated in real-time. Which command should they use?

Question 81hardmulti select

Which TWO statements are true about commit operations in Junos? (Choose two.)

Question 82mediummulti select

Which THREE pipe modifiers can be used to filter command output? (Choose three.)

Question 83easymulti select

Which TWO commands can be used to enter configuration mode from operational mode? (Choose two.)

Question 84easymultiple choice

Refer to the exhibit. Based on the output, which statement is true?

Exhibit

user@router> show configuration | display set
set system host-name router1
set system root-authentication encrypted-password "$5$abcde$xyz..."
set interfaces ge-0/0/0 unit 0 family inet address 10.0.0.1/24
set system login user admin class super-user

Question 85mediummultiple choice

You are a network engineer responsible for a Juniper MX240 router in a data center. The router is running Junos 18.2R1 and you need to upgrade it to 19.1R2 to fix a critical security vulnerability. You establish an SSH session to the router and enter configuration mode to prepare the upgrade. While in configuration mode, you notice that the candidate configuration contains several uncommitted changes from a previous engineer that attempted to modify BGP settings but introduced a syntax error. The candidate configuration fails any commit operation due to this error. The currently active configuration is stable and the router is handling production traffic. The upgrade process requires you to change the boot media and specify the new image. Which action should you take to clear the candidate configuration and proceed with the upgrade?

Question 86hardmultiple choice

You are a network administrator for a large service provider. You have a Juniper MX960 that serves as a core router. The router uses a configuration with many apply-groups to streamline management. Recently, you added a new apply-group for interface-specific policies. After committing, several interfaces stopped passing traffic due to incorrect policy application. You need to quickly revert to the previous configuration without losing other valid changes made by other engineers in the same commit. The previous configuration is stored as rollback 1. However, rollback 1 contains configuration that does not include the new apply-group but also includes other valid changes from the last commit. You want to restore the configuration to exactly the state before the last commit (the rollback 1 state). Which command should you use?

Question 87mediummultiple choice

A network engineer is troubleshooting a BGP session that is not establishing. They want to see the BGP configuration details for peer 10.0.0.1. They type 'show configuration protocols bgp group external peer 10.0.0.1' but receive 'error: syntax error'. They are in operational mode. What is the most likely issue?

Question 88easymulti select

Which two commands can be used to view the candidate configuration in set format? (Choose two.)

Question 89hardmulti select

Which three statements about JunOS CLI pipe commands are true? (Choose three.)

Question 90mediummultiple choice

A network engineer is configuring a Juniper device in a production network. They have applied several changes to the candidate configuration and run 'commit check', which passes. After a brief pause, they run 'commit' but receive the error: 'commit failed: configuration database modified by another user. Please reload the configuration and try again.' The engineer is the only person currently logged into the device, but they know that another engineer was working on the same device earlier and may have left a commit pending. What is the most likely reason for the commit failure?

Question 91hardmultiple choice

A network administrator is trying to configure a firewall filter on a Juniper device. They enter configuration mode and type 'set firewall family inet filter BLOCK-ICMP term 1 from protocol icmp'. They then type 'set firewall family inet filter BLOCK-ICMP term 1 then reject'. After committing, they notice that ICMP traffic is not being blocked. They run 'show configuration firewall' and see the filter is present. They run 'show firewall filter BLOCK-ICMP' to see the counters and notice the packet count is zero. What is the most likely reason?

Question 92easymultiple choice

Review the full OSPF breakdown →

A junior network engineer is learning JunOS CLI and wants to view the last 10 lines of the system log file. They log into the device and type 'show log messages | last 10'. They receive an error: 'unknown pipe command'. Which pipe command should they use instead?

Question 93mediummultiple choice

A network engineer wants to view the OSPF log entries in real time. They type 'show log messages | match ospf' and get output, but it does not update. What should they do to see real-time updates of OSPF log entries?

Question 94hardmultiple choice

A senior network administrator is logged into a Juniper device in operational mode. They need to make a configuration change to the BGP group 'INTERNAL'. They type 'configure terminal' and receive 'unknown command'. They then type 'configure' and enter configuration mode. They make the needed changes and exit configuration mode using 'exit'. They then try to view the active configuration to verify the changes by typing 'show configuration | match INTERNAL'. They see no output. What is the most likely reason?

Question 95easymulti select

Which TWO statements about the Junos CLI are correct?

Question 96mediummultiple choice

Refer to the exhibit. The interface ge-0/0/0 is configured as shown, but the interface is operationally down. Which command would provide the most detailed information about the interface status and errors?

Exhibit

user@router> show configuration interfaces ge-0/0/0
unit 0 {
    family inet {
        address 10.1.1.1/24;
    }
}

Question 97hardmultiple choice