JN0-106 Junos Configuration Basics Practice Test 5 — 15 Questions

Question 1

An administrator is configuring a new Junos device and wants to ensure that configuration changes are applied only after explicit commit confirmation. Which configuration statement should be used?

Accepted Answer

commit confirmed. The 'commit confirmed' statement allows an administrator to apply configuration changes that automatically revert to the previous configuration if not explicitly confirmed within a specified timeout period (default 10 minutes). This ensures changes are only permanently applied after an explicit 'commit' confirmation, providing a safety mechanism to prevent lockout or misconfiguration.

Answer

commit synchronize

Answer

commit at

Answer

commit check

Question 2

A network engineer needs to configure an interface on a Juniper device to use DHCP to obtain an IP address. Which hierarchy is used to apply this configuration?

Accepted Answer

set interfaces ge-0/0/0 unit 0 family inet dhcp. On Juniper devices, DHCP client functionality for IPv4 is configured under the `family inet` hierarchy within a logical interface unit. The command `set interfaces ge-0/0/0 unit 0 family inet dhcp` enables the interface to obtain an IPv4 address via DHCP, which is the standard method for dynamic address assignment on Ethernet interfaces.

Answer

set interfaces ge-0/0/0 dhcp-client

Answer

set interfaces ge-0/0/0 unit 0 family inet6 dhcp

Answer

set interfaces ge-0/0/0 unit 0 family ppp dhcp

Question 3

An administrator is troubleshooting a configuration issue where a route filter is unexpectedly dropping traffic. The filter uses an 'exact' match type. Which statement correctly describes the behavior of the 'exact' match type in a prefix list?

Accepted Answer

The route must match the prefix and prefix length exactly.. The 'exact' match type in a Junos prefix list requires the route's prefix and prefix length to match the specified prefix and length identically. This is defined in the Junos routing policy framework, where 'exact' is used for precise route filtering, such as matching a specific network like 192.168.1.0/24 without allowing any subnets or supernets.

Answer

The route mask must be equal to or greater than the specified prefix length.

Answer

The prefix 0.0.0.0/0 is never matched by 'exact' filters.

Answer

The route mask must be greater than the specified prefix length.

Question 4

A Juniper device has multiple candidate configurations loaded. The administrator wants to discard all uncommitted changes and revert to the last committed configuration. Which command should be used?

Accepted Answer

rollback 0. The 'rollback 0' command reverts the candidate configuration to the last committed configuration, discarding all uncommitted changes. In Junos, the rollback command uses a numeric index where 0 always refers to the most recently committed configuration, effectively undoing any uncommitted edits.

Answer

delete configuration

Answer

clear configuration

Answer

load override terminal

Question 5

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 6

An administrator is configuring a static route to a remote network 10.10.10.0/24 via next-hop 192.168.1.1. Which command correctly adds this route?

Accepted Answer

set routing-options static route 10.10.10.0/24 next-hop 192.168.1.1. The Junos syntax for configuring a static route uses the hierarchy `set routing-options static route next-hop

`. The prefix must include the subnet mask in CIDR notation (e.g., /24). This command installs a route to 10.10.10.0/24 with next-hop 192.168.1.1 into the routing table.

Answer

set routing-options route 10.10.10.0/24 static next-hop 192.168.1.1

Answer

set routing-options static route 10.10.10.0 next-hop 192.168.1.1 mask 255.255.255.0

Answer

set routing-options static next-hop 192.168.1.1

Question 7

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 8

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

Accepted Answer

The commit operation validates syntax before applying, and if errors are found, the commit fails.. Option A is correct because when you run commit, Junos first performs a syntax check on the candidate configuration, and if any syntax errors are detected, the commit fails and the candidate configuration is not activated. Option E is correct because the commit operation merges the candidate configuration into the active configuration, making it the new running (active) configuration on the device. Option B is incorrect because automatic rollback after 10 minutes only occurs with the 'commit confirmed' command, not a standard commit. Option C is incorrect because Junos commits the entire candidate configuration; partial commits are not supported (you would use configuration groups or 'commit check' for validation instead). Option D is incorrect because commit applies changes immediately, not at the next system reboot.

Answer

The commit operation automatically rolls back changes after 10 minutes if not confirmed.

Answer

The commit operation allows you to commit only a specific portion of the configuration.

Answer

The commit operation applies the configuration changes at the next system reboot.

Question 9

Which THREE statements correctly describe the behavior of the 'replace pattern' command in Junos configuration mode?

Accepted Answer

It can be used to change interface names or IP addresses throughout the configuration.. Option C is correct because the 'replace pattern' command performs a global find-and-replace across the candidate configuration, making it ideal for renaming interfaces or changing IP addresses everywhere they appear. Option D is correct because 'replace pattern' edits the candidate configuration, not the active configuration, so changes must still be committed to take effect. Option E is correct because the command matches text using regular expressions (e.g., 'replace pattern ge-0/0/0 with ge-0/0/1'), allowing flexible pattern-based substitutions. Option A is not correct because 'replace pattern' does not itself validate the replacement for correctness before applying; validation occurs at commit time via 'commit check' or the commit process. Option B is not correct because 'replace pattern' does not automatically commit changes; the user must explicitly issue a 'commit' command afterward.

Answer

It validates the replacement configuration for correctness before applying.

Answer

It automatically commits the changes after replacement.

Question 10

An engineer wants to revert all uncommitted changes in the candidate configuration and start fresh from the currently active configuration. Which command should be used?

Accepted Answer

rollback 0. The `rollback 0` command reverts all uncommitted changes in the candidate configuration and restores it to match the currently active configuration (the one most recently committed). This is because Junos stores the last 50 committed configurations, with index 0 always representing the active configuration. Using `rollback 0` effectively discards any uncommitted edits and starts fresh from the last committed state.

Answer

commit check

Answer

rollback 1

Answer

load override terminal

Question 11

During a maintenance window, an engineer issues 'commit confirmed 5' but the change causes a connectivity loss. The engineer is unable to reconnect to the device before the timeout expires. What will happen?

Accepted Answer

The device automatically reverts to the previous active configuration.. The 'commit confirmed 5' command activates a candidate configuration and starts a 5-minute rollback timer. If the engineer does not issue a 'commit' or 'commit check' before the timer expires, Junos automatically reverts to the previously active configuration. This ensures the device returns to a known working state without manual intervention, preserving connectivity after the failed change.

Answer

The engineer must manually rollback using the rollback command.

Answer

The change remains committed until the next reboot.

Answer

The device reloads with factory defaults.

Question 12

An engineer needs to configure a static route on a Juniper device. Which statement is true regarding the configuration process?

Accepted Answer

Configuration changes must be committed to become active.. In Junos, configuration changes are made in a candidate configuration and do not take effect until explicitly committed using the 'commit' command. This two-phase model (edit then commit) ensures that changes are validated before activation, preventing partial or incorrect configurations from disrupting network operations. Option B correctly identifies this requirement.

Answer

The set command activates the change for 10 minutes by default.

Answer

The configuration is immediately active upon entering the set command.

Answer

The commit command requires a reboot to take effect.

Question 13

After a series of configuration changes, an engineer wants to see only the lines that will be added or modified when the candidate is committed. Which command achieves this?

Accepted Answer

show | compare. The 'show | compare' command displays the differences between the candidate configuration and the active configuration, showing only the lines that will be added, modified, or deleted upon commit. This is the standard Junos method for reviewing pending changes before committing them.

Answer

show configuration | except

Answer

show configuration | display set

Answer

commit check | match

Question 14

An engineer issues the 'rollback 3' command in configuration mode. What is the effect?

Accepted Answer

The candidate configuration is replaced with the configuration from three commits ago.. The 'rollback 3' command in Junos configuration mode replaces the current candidate configuration with the configuration from the third most recent commit. Junos maintains up to 50 rollback slots (numbered 0 through 49), where slot 0 is the most recent commit, slot 1 is the commit before that, and so on. Therefore, 'rollback 3' retrieves the configuration saved three commits ago, overwriting any uncommitted changes in the candidate configuration.

Answer

The candidate configuration is saved as the third rollback slot.

Answer

The active configuration is replaced with the candidate configuration.

Answer

The device reboots and loads configuration version 3.

Question 15

A junior administrator is told to implement configuration changes that must survive a reboot. Which statement is correct?

Accepted Answer

Performing a 'commit' saves the active configuration to non-volatile storage.. In Junos, the 'commit' command activates the candidate configuration and saves it to non-volatile storage (the /config directory on the flash drive), ensuring it survives a reboot. This is the standard method for making configuration changes persistent across system restarts.

Answer

The 'commit confirmed' command ensures persistence.

Answer

Changes made using 'set' commands are automatically saved to the startup config.

Answer

The 'commit' command only writes to RAM, so a 'request system configuration save' is needed.