JN0-106 Practice Test 4 — 25 Questions

Question 1

Which THREE actions can be performed in operational mode on a Junos device?

Accepted Answer

Ping a remote host. In Junos, operational mode is the CLI mode entered after login (prompt user@host>), used for monitoring and controlling device state. Option B (Ping a remote host) is correct because the ping command is an operational-mode command used to test reachability to a remote host. Option D (View system logs) is correct because operational mode provides commands such as show log messages to inspect system log files. Option E (Reboot the chassis) is correct because the request system reboot command is executed from operational mode to restart the device. Options A and C are not operational-mode actions: committing configuration changes (commit) and configuring interface IP addresses (set interfaces ...) are performed in configuration mode, which is entered with the configure command.

Answer

Commit configuration changes

Answer

Configure interface IP addresses

Question 2

Which TWO statements about the rescue configuration are correct? (Choose two.)

Accepted Answer

The rescue configuration is designed to provide a method of last-resort recovery.. Option C is correct because the rescue configuration exists specifically as a last-resort recovery mechanism, allowing an administrator to return a device to a known-good configuration when the active configuration is broken or inaccessible. Option D is correct because on Junos devices the rescue configuration is created and stored by running the operational-mode command 'request system configuration rescue save', which snapshots the current candidate configuration as the rescue configuration. Option A is wrong because the rescue configuration is not saved automatically on every commit; it must be saved explicitly by the administrator. Option B is wrong because 'rollback rescue' loads the previously saved rescue configuration, not the factory-default configuration, which would be loaded with 'load factory-default' or 'rollback 0' depending on context. Option E is wrong because the rescue configuration restores the entire saved configuration, not just a subset of it.

Answer

The rescue configuration is automatically saved after every commit.

Answer

The 'rollback rescue' command loads the factory-default configuration.

Answer

The rescue configuration can be used to restore only a subset of the configuration.

Question 3

An engineer needs to check the last time the configuration was changed. Which command provides this information?

Accepted Answer

show system commit. The 'show system commit' command displays the commit history, including the date, time, and user for each configuration change. This allows the engineer to see exactly when the last configuration was committed, which is the definitive way to determine the last time the configuration was changed.

Answer

show configuration | display set

Answer

show system alarms

Answer

show system uptime

Question 4

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

Accepted Answer

'show' shows the candidate configuration; 'run show configuration' shows the active configuration.. In Junos, when you are in configuration mode and type 'show', it displays the candidate configuration (the changes you have made but not yet committed). The command 'run show configuration' executes the operational-mode command 'show configuration' from within configuration mode, which displays the active (committed) configuration. Therefore, option B correctly identifies that 'show' shows the candidate configuration and 'run show configuration' shows the active configuration.

Answer

'show' shows the active configuration; 'run show configuration' shows the candidate.

Answer

Both commands produce identical output.

Answer

'run show configuration' is not allowed from configuration mode.

Question 5

Which THREE of the following are characteristics of configuration groups in Junos?

Accepted Answer

The 'apply-groups' statement is used to specify which group(s) should be inherited.. Option A is correct because Junos uses the 'apply-groups' statement (and 'apply-groups-except') to specify which configuration group(s) a given hierarchy level should inherit from. Option C is correct because Junos configuration groups support nesting: a group can itself contain an 'apply-groups' statement, allowing one group to inherit from another group. Option D is correct because the core purpose of configuration groups is to define a reusable set of configuration statements once and have them inherited by multiple sections of the configuration, reducing duplication. Option B is incorrect because there is no limit of 10 groups per statement; Junos allows up to 50 groups to be applied at a single hierarchy level. Option E is incorrect because statements inherited from a group can be overridden by explicitly configuring the same statement in the main configuration, which takes precedence over the inherited value.

Answer

A maximum of 10 groups can be applied to a single configuration statement.

Answer

Configuration groups do not allow individual statements within the group to be overridden in the main configuration.

Question 6

Which two statements correctly describe Junos OS login classes? (Choose two.)

Accepted Answer

They are defined under the [edit system login class] hierarchy.. Option B is correct because login classes are configured at the [edit system login class class-name] hierarchy in Junos OS, where you define permissions and other login parameters. Option D is correct because a login class can include or exclude the configure permission, thereby restricting whether a user can enter configuration mode. Options A, C, and E are incorrect: login classes do not force operational-mode-only access (that depends on permissions such as configure), they are not automatically assigned to all users by default (each user must be associated with a class, otherwise the default class applies), and they can be modified or deleted after creation.

Answer

They allow users to enter only operational mode.

Answer

They are automatically assigned to all users by default.

Answer

They cannot be modified after creation.

Question 7

A BGP session is flapping. The engineer runs 'show log messages' and sees 'BGP recv Notification' with error code 'Cease'. What does this indicate?

Accepted Answer

The remote peer closed the connection. A BGP Cease notification indicates that the remote peer has closed the BGP session, often due to an administrative shutdown, configuration change, or error condition on the peer. The 'BGP recv Notification' message means the local router received this notification from the peer, so the remote peer initiated the closure.

Answer

The BGP table is full

Answer

The hold timer expired

Answer

The interface went down

Question 8

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

Accepted Answer

monitor interface traffic. The `monitor interface traffic` command in Junos OS provides a real-time, continuously updating display of interface traffic statistics, making it the correct choice for live monitoring. Unlike static commands that show a single snapshot, this command refreshes the output at a default interval (typically 1 second) until the user interrupts it with Ctrl+C.

Answer

show interface statistics

Answer

monitor start messages

Answer

show interfaces extensive

Question 9

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?

Accepted Answer

show route table inet.0. The command 'show route table inet.0' displays the IPv4 unicast route table in Junos. The inet.0 table is the default routing table for IPv4 unicast routes, containing all active routes learned via various protocols (e.g., OSPF, BGP, static). This command is the standard way to view the IPv4 unicast routing information base (RIB) on Juniper devices.

Answer

show route table inet6.0

Answer

show route forwarding-table

Answer

show route protocol bgp

Question 10

Refer to the exhibit. What does this output indicate?

Accepted Answer

The candidate configuration differs from the active configuration.. The output shows the 'show | compare' command, which displays the differences between the candidate configuration and the active (committed) configuration. The presence of lines prefixed with '+' (additions) and '-' (deletions) indicates that the candidate configuration is not identical to the active configuration, confirming that they differ.

Answer

There is a syntax error.

Answer

The commit succeeded.

Answer

The configuration is identical.

Question 11

A junior engineer is tasked with configuring a firewall filter to only allow SSH access to the management interface. The management interface is fxp0. Which configuration is correct?

Accepted Answer

set interfaces fxp0 unit 0 family inet filter input allow-ssh. The management interface on Juniper devices is fxp0, and applying a firewall filter to its inet family input direction restricts inbound traffic. The filter 'allow-ssh' must permit only TCP port 22, blocking all other management access. This configuration ensures SSH-only access to the management interface.

Answer

set interfaces lo0 unit 0 family inet filter input allow-ssh

Answer

set groups management-filter interfaces fxp0 unit 0 family inet filter input allow-ssh

Answer

set interfaces ge-0/0/0 unit 0 family inet filter input allow-ssh

Question 12

Refer to the exhibit. The router has three static routes configured. Which route will be used to forward a packet destined to 172.16.1.100?

Accepted Answer

The static route to 172.16.0.0/16. The router will use the most specific matching route for the destination 172.16.1.100. The static route to 172.16.0.0/16 has a prefix length of 16, which is more specific than the default route (0.0.0.0/0) and the route to 10.0.0.0/8 (which does not match the destination). Therefore, the route to 172.16.0.0/16 is selected based on the longest-prefix-match rule.

Answer

The default route (0.0.0.0/0)

Answer

The router will drop the packet.

Answer

The static route to 10.0.0.0/8

Question 13

When configuring OSPF on a Juniper router, an engineer applies the 'area 0.0.0.0 interface ge-0/0/1.0 passive' command. What is the effect of this configuration?

Accepted Answer

The interface will not send OSPF hellos, but the connected network will still be advertised in OSPF.. The 'passive' configuration on an OSPF interface in Junos prevents the interface from sending OSPF Hello packets, which stops the formation of neighbor adjacencies. However, the interface's connected network prefix is still advertised as a stub network in OSPF Type 1 LSAs, ensuring reachability to that subnet without dynamic neighbor relationships.

Answer

The interface will not be advertised in OSPF at all, and no OSPF traffic will be transmitted.

Answer

The interface will only accept incoming OSPF packets but will not send any.

Answer

The interface will actively send OSPF hellos and attempt to form adjacencies.

Question 14

Refer to the exhibit. An engineer has made changes to the candidate configuration. What will happen when the engineer issues the 'commit' command?

Accepted Answer

Both the interface address and security policy will be activated.. In Junos, the 'commit' command activates all changes in the candidate configuration atomically. Both the interface address change and the security policy will be applied simultaneously after validation. Junos does not require a reboot for security policy changes, and syntax errors cause the commit to fail, not be ignored.

Answer

The commit will succeed but the security policy will be ignored due to a syntax error.

Answer

Only the interface address change will be committed because security policies require a reboot.

Answer

The configuration will be validated; if errors exist, the commit will fail.

Question 15

An administrator suspects that an interface is flapping but the router is remote and the connection is intermittent. The administrator wants to monitor the interface status without maintaining an SSH session. Which approach should be used?

Accepted Answer

Configure event-options to trigger on interface down and send syslog. Junos event-options allows you to define an event policy that triggers on a specific event, such as an interface down transition, and then executes an action like sending a syslog message. This enables asynchronous monitoring without requiring an active SSH session, making it ideal for intermittent connectivity scenarios.

Answer

Use 'monitor interface ge-0/0/0' and rely on terminal persistence

Answer

Use 'monitor start' to capture logs

Answer

Schedule a cron job to run 'show interfaces ge-0/0/0' every minute and log output

Question 16

What is the default behavior when a user logs in to a Junos device and enters configuration mode?

Accepted Answer

The user can edit the candidate configuration.. When a user enters configuration mode on a Junos device, they are placed into a private copy of the candidate configuration. This allows the user to make changes without affecting the active configuration until a commit operation is performed. Option B correctly describes this default behavior.

Answer

The user must first commit before making changes.

Answer

The user can only view the configuration.

Answer

The user directly modifies the active configuration.

Question 17

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

Accepted Answer

network. Network. In Junos, the 'network' permission bit controls access to network diagnostic commands such as ping, traceroute, and ssh. Without this permission, a user cannot execute these commands even if they have other permissions like view or control.

Answer

view

Answer

control

Answer

system

Question 18

A network engineer needs to verify the checksum of a downloaded Junos image before installation. Which command is used?

Accepted Answer

file checksum sha256 . The `file checksum sha256 ` command computes the SHA-256 hash of the specified file, allowing the engineer to compare it against the published checksum from Juniper Networks to verify integrity and authenticity before installation. This ensures the image has not been corrupted or tampered with during download.

Answer

compare <filename> original

Answer

request system software validate <filename>

Answer

show system software

Question 19

A company uses a Juniper MX router to connect two branch offices via a point-to-point link. The link is flapping. Which command would you use to check the interface errors on the link?

Accepted Answer

show interfaces ge-0/0/0 extensive. The 'show interfaces ge-0/0/0 extensive' command provides detailed interface statistics, including error counters such as CRC errors, frame errors, and link state transitions. This is the most comprehensive command to diagnose why a point-to-point link is flapping, as it reveals physical-layer issues that cause the interface to go up/down repeatedly.

Answer

show log messages

Answer

show configuration interfaces ge-0/0/0

Answer

show interfaces ge-0/0/0 terse

Question 20

A network administrator is troubleshooting high CPU usage on a Juniper router. Which command helps identify which process is consuming the most CPU?

Accepted Answer

show system processes extensive. The 'show system processes extensive' command displays detailed information about all running processes, including CPU utilization, memory usage, and process IDs. This allows the administrator to identify which process (e.g., routing protocol daemon, management daemon) is consuming the most CPU cycles, directly addressing the troubleshooting need.

Answer

show log messages

Answer

show system memory

Answer

show interfaces