JNCIA-JUNOS Junos Configuration Basics Practice Test 2 — 15 Questions

Question 1

An engineer needs to apply a configuration change that adds a new static route to the Junos device. The engineer wants to ensure the change takes effect immediately and is persistent across reboots. Which command should the engineer use?

Accepted Answer

commit. The 'commit' command is correct because it immediately activates the candidate configuration (including the new static route) and makes it the active configuration that survives a reboot. Junos uses a two-stage configuration model where changes are first made to the candidate configuration and then committed to become the active, persistent configuration.

Answer

load override

Answer

commit confirmed

Answer

rollback

Question 2

Which TWO statements about configuration groups in Junos are correct? (Choose two.)

Accepted Answer

Configuration groups are defined under the [edit groups] hierarchy.. Option A is correct because configuration groups in Junos are defined under the [edit groups] hierarchy. This allows you to create reusable configuration snippets that can be applied to multiple parts of the configuration, reducing duplication and simplifying management.

Answer

Configuration groups are stored in separate files that are imported using the 'file' statement.

Answer

The 'replace' tag is used to reference a configuration group.

Answer

Configuration groups are applied only at the [edit interfaces] hierarchy level.

Question 3

Refer to the exhibit. An engineer configures interface ge-0/0/0 with both IPv4 and IPv6 addresses. The engineer notices that the interface is operationally up, but the IPv6 address is not pingable from a directly connected host. The host has an IPv6 address in the same subnet. What is the most likely cause?

Accepted Answer

The interface does not have IPv6 neighbor discovery enabled.. IPv6 neighbor discovery (ND) is required for address resolution and duplicate address detection on a link. If ND is not enabled on the interface, the router cannot respond to Neighbor Solicitation messages from the host, making the IPv6 address unreachable even though the interface is operationally up. In Junos, ND is enabled by default on IPv6-enabled interfaces, but it can be disabled with the 'no-neighbor-discovery' configuration statement.

Answer

The interface MTU is too small for IPv6 packets.

Answer

The IPv6 address is not configured under the correct unit.

Answer

The interface has an IPv4 address, which prevents IPv6 from working.

Question 4

Your company has deployed a Juniper MX router at a branch office. The router has two upstream connections to different ISPs. The configuration currently uses a single static default route to ISP-A. The network team wants to add redundancy so that if ISP-A fails, traffic automatically uses ISP-B. The ISP-B connection is already configured on interface ge-1/0/0 with IP address 203.0.113.2/30. The next-hop IP for ISP-B is 203.0.113.1. The routing table should have a backup default route with a higher metric. Which configuration change meets the requirement?

Accepted Answer

set routing-options static route 0.0.0.0/0 next-hop 203.0.113.1 metric 2. Option C is correct because it adds a static default route to ISP-B with a metric of 2, which is higher than the default metric of 0 (or 1 if explicitly set) for the existing route to ISP-A. In Junos, when multiple static routes to the same destination exist, the route with the lower metric (preference) is installed in the routing table. If the primary route fails (e.g., interface down), the route with the higher metric becomes active, providing automatic failover.

Answer

set routing-options static route 0.0.0.0/0 next-hop 203.0.113.1 metric 1

Answer

set routing-options static route 0.0.0.0/0 discard

Answer

set routing-options static route 0.0.0.0/0 next-table inet.0

Question 5

An engineer needs to apply a configuration change to the Junos device that must survive a reboot. Which configuration mode command should be used to save the changes?

Accepted Answer

commit. The 'commit' command is the standard way to apply a candidate configuration to the active configuration in Junos. When you issue 'commit', the changes are saved to the /config/juniper.conf.gz file, which is loaded upon reboot, ensuring the configuration survives a restart.

Answer

commit confirmed

Answer

commit synchronize

Answer

commit check

Question 6

Which TWO statements correctly describe Junos configuration hierarchy and management?

Accepted Answer

The 'load merge' command imports configuration from a file and merges it with the current candidate configuration.. Option B is correct because the 'load merge' command in Junos imports configuration data from a file and merges it with the current candidate configuration, preserving existing statements unless explicitly overridden. This allows incremental changes without replacing the entire configuration, which is essential for efficient network operations.

Answer

The 'deactivate' command permanently removes a configuration statement from the candidate.

Answer

The 'set' command in configuration mode directly modifies the active configuration.

Answer

In operational mode, the 'show' command displays the candidate configuration.

Question 7

Refer to the exhibit. What is the purpose of the 'family inet6' configuration on interface ge-0/0/0?

Accepted Answer

To assign a global unicast IPv6 address to the interface.. The 'family inet6' configuration on interface ge-0/0/0 enables IPv6 processing on that interface. Within the 'family inet6' hierarchy, you can assign a global unicast IPv6 address using the 'address' statement. Without 'family inet6', the interface cannot process IPv6 traffic or hold an IPv6 address, making option B correct.

Answer

To enable both IPv4 and IPv6 on the interface.

Answer

To enable IPv6 ARP on the interface.

Answer

To assign a link-local IPv6 address to the interface.

Question 8

Order the steps to configure a VLAN on an EX Series switch running Junos.

Question 9

Order the steps to configure a BGP peering session in Junos.

Question 10

Match each Junos configuration mode command to its purpose.

Question 11

Match each Junos software process to its role.

Question 12

An administrator makes changes to the candidate configuration and wants to automatically revert to the previous configuration if the changes cause a loss of connectivity. Which method should be used?

Accepted Answer

Use the 'commit confirmed' command.. The 'commit confirmed' command is the correct method because it allows an administrator to commit a candidate configuration with a confirmation timeout (default 10 minutes). If connectivity is lost and the commit is not confirmed within the timeout, Junos automatically reverts to the previous configuration, ensuring the device remains reachable.

Answer

Use the 'commit check' command.

Answer

Use the 'commit synchronize' command.

Answer

Use the 'rollback' command.

Question 13

A network engineer wants to quickly restore the device to a known good configuration after a failed change. What is the recommended approach?

Accepted Answer

Use the 'rollback rescue' command.. Option C is correct because the 'rollback rescue' command restores the device to the rescue configuration, which is a known good configuration saved explicitly for recovery after a failed change. The rescue configuration is stored as a separate file and is not affected by normal commit operations, making it the recommended approach for quick restoration.

Answer

Use the 'request system configuration rescue save' command.

Answer

Use the 'rollback 0' command.

Answer

Use the 'load override terminal' command.

Question 14

Which configuration group feature allows an administrator to apply common configuration settings to multiple interfaces without repeating the configuration?

Accepted Answer

apply-groups. The `apply-groups` statement is the correct feature because it allows an administrator to define a common configuration template within a `groups` hierarchy and then apply that template to multiple interfaces (or other configuration sections) using the `apply-groups` command. This avoids repeating the same configuration statements across individual interfaces, streamlining management and reducing errors.

Answer

groups statement

Answer

interface-range

Answer

apply-path

Question 15

An administrator wants to apply the same BGP configuration to all interfaces whose names start with 'ge-'. Which approach would dynamically match these interfaces?

Accepted Answer

Use apply-path referencing a regular expression in the configuration group. Option C is correct because the `apply-path` statement in a configuration group can dynamically match interfaces based on a regular expression pattern. By using `apply-path` with a regular expression like `ge-*` inside the configuration group, Junos will automatically apply the BGP configuration to all interfaces whose names match that pattern without manual enumeration.

Answer

Define a configuration group and use apply-groups with [edit interfaces ge-*]

Answer

Create a firewall filter that matches ge- interfaces

Answer

Use an interface-range named 'ge-interfaces' listing all ge- interfaces