JN0-106 Junos OS Fundamentals Practice Test 5 — 15 Questions

Question 1

What is the primary function of the fxp0 interface on a Juniper device?

Accepted Answer

Management interface. The fxp0 interface is a dedicated out-of-band management Ethernet port on Juniper devices, used exclusively for management traffic such as SSH, SNMP, and syslog. It is separate from the data plane and control plane forwarding interfaces, ensuring administrative access remains available even if the routing or forwarding planes are disrupted.

Answer

Internal routing

Answer

Loopback testing

Answer

Data plane forwarding

Question 2

Refer to the exhibit. An administrator wants to ensure that log messages are stored even if the remote syslog server becomes unavailable. What additional configuration is required?

Accepted Answer

set system syslog file messages any any. Configuring a local log file with `set system syslog file messages any any` ensures that log messages are stored locally on the device, even if the remote syslog server becomes unavailable. This provides a persistent local copy of logs that can be reviewed later, independent of the remote server's reachability.

Answer

set system syslog archive world-readable

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set system syslog host 10.10.10.1 facility-override

Answer

set system syslog rate-limit 1000

Question 3

Refer to the exhibit. An administrator notices repeated failed login attempts. What should be configured to mitigate this attack?

Accepted Answer

Configure a firewall filter to block the source IP. A firewall filter can block traffic from the source IP address of the repeated failed login attempts, preventing further access from that host. This is a direct and immediate mitigation against an ongoing brute-force attack, as it stops the attacker's traffic at the network layer before it reaches the SSH or login service.

Answer

Set login retry limit

Answer

Disable SSH

Answer

Change the root password

Question 4

An engineer wants to roll back to the previous configuration. Which command should be used?

Accepted Answer

rollback 1. The `rollback 1` command loads the previous committed configuration (the configuration before the last commit) into the candidate configuration, discarding any uncommitted changes. This allows the engineer to replace the current candidate with the desired historical configuration. In Junos, `rollback 0` loads the most recently committed configuration (the current active configuration), not the previous one.

Answer

delete

Answer

rollback 0

Answer

commit check

Question 5

A Junos device has multiple configuration files saved. Which command shows the available rollback configurations?

Accepted Answer

show system commit. The 'show system commit' command displays a list of all committed configuration revisions, including their commit IDs and timestamps, which are used to roll back to a previous configuration. The rollback feature in Junos relies on these stored commit files, and the command explicitly shows the available rollback points.

Answer

show system configuration

Answer

show system rollback

Answer

show configuration | display rollback

Question 6

What happens when a user issues the 'request system reboot' command without any options?

Accepted Answer

The device prompts for confirmation.. When a user issues the 'request system reboot' command without any options, Junos OS prompts for confirmation before proceeding. This is a safety mechanism to prevent accidental reboots, as the command does not automatically reboot the device immediately or schedule a delayed reboot by default.

Answer

The device reboots after the current commit.

Answer

The device reboots immediately.

Answer

The device schedules a reboot in 5 minutes.

Question 7

Which TWO statements are true regarding Junos configuration groups?

Accepted Answer

Configuration groups are applied using the apply-groups statement.. Option B is correct because configuration groups in Junos are explicitly attached to the configuration hierarchy using the apply-groups statement (for example, set interfaces ge-0/0/0 apply-groups GROUP-NAME), which is the mechanism that injects the group's statements into the active configuration. Option E is correct because when multiple groups are referenced in an apply-groups statement, Junos processes them in the order listed, with later groups taking precedence over earlier ones, and the explicit configuration taking precedence over all applied groups. Option A is wrong because group settings can override existing settings depending on inheritance and precedence rules. Option C is wrong because configuration groups can contain almost any configuration stanza, not just interfaces. Option D is wrong because groups are not applied automatically to all hierarchies; they must be explicitly referenced with apply-groups at the desired hierarchy level.

Answer

Configuration groups never override existing settings.

Answer

Configuration groups are only useful for interface configuration.

Answer

Configuration groups are applied automatically to all hierarchies.

Question 8

A network administrator needs to remove all configuration changes made since the last commit without affecting the current active configuration. Which command should be used?

Accepted Answer

rollback 0. The `rollback 0` command reverts the candidate configuration to the currently active committed configuration, discarding all uncommitted changes without affecting the active configuration. This is the correct way to undo all modifications made since the last commit while keeping the running configuration intact.

Answer

rollback 1

Answer

deactivate

Answer

delete

Question 9

An engineer wants to view the current active configuration file that the device is using. Which command displays this information?

Accepted Answer

show configuration. The 'show configuration' command displays the current active configuration that the device is using, which is the committed configuration stored in /config/juniper.conf.gz. This command reads the active configuration file directly from the file system, showing the exact operational configuration that Junos applies to the device.

Answer

show configuration candidates

Answer

show system commit

Answer

show configuration | display set

Question 10

A technician is troubleshooting a device that has an inconsistent configuration. They need to revert to the configuration that was committed exactly two commits ago. Which command sequence accomplishes this?

Accepted Answer

rollback 2 followed by commit. The `rollback 2` command reverts the candidate configuration to the state it was in two commits ago, but the change is not applied until a `commit` is issued. This two-step sequence (rollback followed by commit) is required to make the reverted configuration active. Without the commit, the device continues running the current active configuration.

Answer

rollback 2

Answer

commit confirmed 2

Answer

rollback 3

Question 11

A technician needs to upgrade the Junos OS on a device that is part of a redundant cluster. Which approach minimizes traffic disruption?

Accepted Answer

Upgrade one node at a time, ensuring the cluster remains redundant.. Upgrading one node at a time in a redundant cluster ensures that at least one node remains active to handle traffic while the other is being upgraded. This approach maintains cluster redundancy and minimizes traffic disruption, as the active node continues forwarding traffic using the gratuitous ARP or VRRP mechanisms, and the upgraded node rejoins the cluster after reboot.

Answer

Use 'request system software add' on both nodes at the same time.

Answer

Upgrade both nodes simultaneously to reduce maintenance time.

Answer

Use the 'commit synchronize' command to keep configurations in sync after upgrade.

Question 12

Which command saves the current operational state information to a file that can be provided to Juniper support for troubleshooting?

Accepted Answer

request support information. The 'request support information' command collects a comprehensive snapshot of the current operational state, including configuration, logs, routing tables, and interface statistics, and packages it into a file (e.g., /var/tmp/support-info-date-time.tgz) that can be directly provided to Juniper support for troubleshooting. This is the standard Junos method for gathering diagnostic data.

Answer

monitor traffic

Answer

show system information

Answer

file copy

Question 13

Which THREE commands are valid in Junos operational mode? (Choose three.)

Accepted Answer

show interfaces terse. Option A, 'show interfaces terse', is valid in Junos operational mode because show commands are operational-mode commands used to display interface status and configuration summaries. Option D, 'ping 10.0.0.1 count 5', is valid in operational mode because ping is an operational-mode diagnostic command, and 'count 5' correctly limits the number of ICMP echo requests. Option E, 'request system software add /var/tmp/junos-install.tgz', is valid in operational mode because request commands are operational-mode commands used to perform system actions such as installing a Junos software package. Option B, 'set interfaces ge-0/0/0 unit 0 family inet address 10.0.0.1/24', is a configuration-mode command and is not valid in operational mode. Option C, 'commit and-quit', is also a configuration-mode command used to commit candidate configuration changes and exit configuration mode, so it is not valid in operational mode.

Answer

set interfaces ge-0/0/0 unit 0 family inet address 10.0.0.1/24

Answer

commit and-quit

Question 14

Refer to the exhibit. An operator tries to ping 192.168.1.2 from this router and fails. The router can ping itself (192.168.1.1). What is the most likely cause?

Accepted Answer

The remote host is not reachable or is not responding to ARP requests.. The router can ping its own interface (192.168.1.1), confirming that the interface is up and IP is configured correctly. The failure to ping 192.168.1.2 indicates that the router cannot reach the remote host, most likely because the host is down, not connected, or not responding to ARP requests. ARP resolution is required for the router to map the destination IP to a MAC address on the local subnet; without a successful ARP reply, the router cannot send the echo request.

Answer

Reverse path forwarding (RPF) check is dropping the echo request.

Answer

The interface is administratively down.

Answer

Proxy ARP is not configured on the interface.

Question 15

Refer to the exhibit. A security analyst sees repeated login failures from 10.0.0.2 for user1. Which Junos feature can be used to automatically block further login attempts from that IP?

Accepted Answer

Apply a firewall filter to the loopback interface that polices SSH traffic.. Applying a firewall filter to the loopback interface (lo0) that polices SSH traffic can automatically block further login attempts from a specific IP address, such as 10.0.0.2. The loopback interface is the termination point for all control-plane traffic on a Junos device, including SSH sessions. By configuring a firewall filter with a policer that limits the rate of SSH packets from a source IP, excessive login failures can trigger the policer to drop subsequent packets, effectively blocking the attacker without manual intervention.

Answer

Configure SSH to accept only public key authentication for user1.

Answer

Disable the user1 account.

Answer

Set the 'session-limit' for user1 to prevent multiple login attempts.