JN0-106 User Interfaces Practice Test 5 — 15 Questions

Question 1

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?

Accepted Answer

rollback 0. The 'rollback 0' command reverts all uncommitted changes and restores the active configuration to the last committed configuration. In Junos, candidate configurations are stored in numbered rollback slots (0 being the most recent committed configuration), so 'rollback 0' discards any uncommitted edits and loads the last committed state.

Answer

rollback 1

Answer

load override terminal

Answer

commit check

Question 2

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?

Accepted Answer

commit confirmed 10. The `commit confirmed 10` command commits the candidate configuration and starts a 10-minute timer. If the commit is not explicitly confirmed with another `commit` command within that time, Junos automatically reverts to the previous configuration. This is the correct method for a timed automatic rollback after a commit.

Answer

commit at 10

Answer

set system commit timer 10

Answer

commit check

Question 3

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?

Accepted Answer

file show. The 'file show' command in Junos operational mode is used to display the contents of a file stored on the device's hard disk, such as a configuration file. Unlike 'show configuration', which displays the active candidate or committed configuration, 'file show' reads the raw file from the filesystem, making it the correct choice for viewing a stored configuration file.

Answer

show configuration

Answer

file list

Answer

view file

Question 4

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

Accepted Answer

show interfaces. In Junos configuration mode, the 'show interfaces' command displays only the interfaces configuration block without leaving configuration mode. This is a Junos-specific feature where 'show' commands within configuration mode show the current candidate configuration, not operational state. The command filters the output to show only the 'interfaces' hierarchy, allowing the administrator to review just that section.

Answer

show

Answer

display set | match interfaces

Answer

run show interfaces

Question 5

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?

Accepted Answer

An error message is displayed, and no changes are made.. In Junos OS, the 'set' command is a configuration mode command used to modify the candidate configuration. When entered in operational mode (indicated by the '>' prompt), the CLI does not recognize it as a valid operational command. Junos will immediately display an error message such as 'unknown command' and make no changes to the running or candidate configuration.

Answer

The IP address is configured successfully.

Answer

The command is queued for later execution.

Answer

The CLI automatically switches to configuration mode.

Question 6

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

Accepted Answer

monitor interface. The 'monitor interface' command in Junos provides real-time, continuously updated packet statistics for a specified interface, making it the correct choice for live troubleshooting. Unlike static commands, it refreshes statistics every second until interrupted, allowing the administrator to observe traffic patterns as they occur.

Answer

traceoptions

Answer

show interfaces statistics

Answer

show interfaces extensive

Question 7

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

Accepted Answer

show configuration | display set. Option C, `show configuration`, is correct because it displays the active configuration in Junos's hierarchical (curly-brace) format, which is the standard way to view the currently committed configuration. Option A, `show configuration | display set`, is also correct because it renders that same active configuration as flat `set` commands, which is useful for viewing or copying the configuration in a script-friendly form. Both commands read the committed active configuration, so they satisfy the requirement. Option B, `show system configuration`, is not a valid Junos operational command for displaying the configuration. Option D, `show | compare`, only shows the difference between the candidate configuration and the active configuration (a diff), not the full active configuration. Option E, `show interfaces`, displays interface status and statistics rather than the device configuration.

Answer

show system configuration

Answer

show | compare

Answer

show interfaces

Question 8

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

Accepted Answer

The default timeout is 10 minutes.. Option B is correct because the 'commit confirmed' command in Junos OS uses a default rollback timeout of 10 minutes, during which the configuration is active but not yet permanent. Option E is correct because the commit only becomes permanent if the administrator issues a confirming 'commit' command within that timeout window; otherwise, the device automatically rolls back to the previous configuration. Option A is incorrect because scheduling a commit for a future time is done with the 'commit at' command, not 'commit confirmed'. Option C is incorrect because 'commit confirmed' does not save the configuration to a file before applying; it applies the candidate configuration with an automatic rollback timer. Option D is incorrect because the timeout can be set to any value from 1 to 65,535 minutes using the 'commit confirmed <minutes>' syntax, not only in multiples of 5 minutes.

Answer

It is used to schedule a commit at a future time.

Answer

It saves the configuration to a file before applying.

Answer

The timeout can be set only in multiples of 5 minutes.

Question 9

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

Accepted Answer

configure private. In Junos, the CLI configuration mode can be entered with different locking behaviors: 'configure private' (option B) gives each user a private candidate configuration so concurrent users don't interfere, 'configure shared' (option C) lets multiple users edit the same shared candidate configuration, and 'configure exclusive' (option E) locks the candidate configuration so only one user can make changes at a time. These three are valid Junos commands for entering configuration mode with the specified locking semantics. Options A ('configure static') and D ('configure dynamic') are not valid Junos configuration-mode commands; there is no 'static' or 'dynamic' configure variant in Junos.

Answer

configure static

Answer

configure dynamic

Question 10

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

Accepted Answer

The interface is up and the physical link is up.. When an interface shows 'Admin up' and 'Link up', it means the interface has been administratively enabled (no 'shutdown' command applied) and the physical layer has detected a carrier signal from the connected device. In Junos, this is the normal operational state for a functioning interface, confirming that both the administrative configuration and the physical link are active.

Answer

The interface is administratively down.

Answer

The interface is a loopback interface.

Answer

The interface has an IPv6 address only.

Question 11

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

Accepted Answer

The candidate configuration has an IP address change.. The output shows the candidate configuration differs from the committed configuration, as indicated by the 'show | compare' command displaying a change under the [edit interfaces ge-0/0/0 unit 0 family inet] hierarchy. Specifically, it shows the address 192.168.1.1/24 being replaced with 192.168.1.2/24, which is an IP address change. This confirms option B is correct because the candidate configuration has an IP address change that has not yet been committed.

Answer

The candidate configuration matches the committed configuration.

Answer

The rollback 0 configuration is being displayed.

Answer

The interface ge-0/0/0 has been deleted.

Question 12

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 13

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?

Accepted Answer

commit check. The 'commit check' command validates the candidate configuration for syntax errors without committing it. When a syntax error like a missing closing brace is present, commit check outputs the exact line number and file where the error occurs, allowing the admin to locate and fix the issue before attempting a commit again.

Answer

rollback 0

Answer

load merge

Answer

show configuration

Question 14

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?

Accepted Answer

rollback 0. The 'rollback 0' command reverts the candidate configuration to the most recently committed configuration (the current active configuration), discarding any uncommitted changes. This allows the administrator to undo the accidental deletion without affecting any recently committed correct changes, as those are already part of the active configuration. Option B, 'rollback 1', would revert to the previous commit, which could remove recently committed correct changes if they were made in the most recent commit. Therefore, 'rollback 0' is the safer choice when you want to preserve correct changes that have already been committed.

Answer

deactivate

Answer

rollback 1

Answer

delete

Question 15

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

Accepted Answer

monitor start messages. The 'monitor start messages' command is used in Junos OS to display system log messages in real time as they are generated. This is the correct command for live monitoring of system events, similar to 'tail -f' on Unix systems.

Answer

show system log

Answer

start shell

Answer

show log messages