F5CAB4 F5 BIG-IP Administration Control Plane Administration (F5CAB4) exam Free Practice Exam Questions (2026 Updated)

A BIG-IP device group cannot be deleted if it still contains device members, even if one of those devices has already been decommissioned or is unreachable. Before deleting the device group, the administrator must explicitly remove the decommissioned device from the device group configuration.

Once the removed or unreachable device is deleted from the device group membership, the BIG-IP system allows the remaining administrator to successfully delete the device group.

Why the other options are incorrect:

A. Remove all members from the device groupThis is not required; the key requirement is removing the decommissioned device, not all members.

B. Make sure all members are in syncSynchronization status does not prevent device group deletion.

D. Disable the device groupDevice groups cannot be disabled; they must be modified or deleted.

Therefore, the correct prerequisite action is to remove the decommissioned device from the device group, making C the correct answer.

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The audit log (/var/log/audit) records configuration changes made on the BIG-IP system, including:

Who made the change (user account)

What was changed (for example, a virtual server modification)

When the change occurred

How it was performed (GUI, TMSH, or API)

Why the other options are incorrect:

/var/log/secure logs authentication events such as login successes and failures, not configuration changes.

/var/log/ltm logs traffic-management and runtime LTM events, not administrative configuration modifications.

Therefore, the correct log file for tracking who changed a virtual server is /var/log/audit.

Connectivity management requires a proper logical-to-physical mapping within the BIG-IP Control Plane.

VLAN Association: In TMOS, a Self IP address is not assigned directly to a physical interface. Instead, it is assigned to a VLAN (Virtual Local Area Network) object.

Procedural Troubleshooting: If a Self IP is unreachable, the primary failure point is often that the IP was associated with the wrong VLAN, or the VLAN itself is not correctly associated with the intended physical interface or trunk.

Layer 2 Mapping: The Control Plane requires the VLAN to be "up" and "untagged" or "tagged" on a valid interface for traffic to flow. If the administrator selects the incorrect VLAN, the Self IP will exist in the configuration but will be logically isolated from the physical network wire.

Reporting device status includes monitoring physical resource exhaustion, such as memory. The Control Plane provides both a command-line method via TMSH (show /sys memory) and a graphical method under Statistics > Module Statistics > Memory to report on how memory is allocated across TMM and the Linux host494949494949494949. This is essential for identifying potential "Aggressive Mode" triggers or hardware performance bottlenecks50.

On a BIG-IP system, remote syslog server configuration is managed through the logging configuration framework. In the Configuration Utility, this is accessed via:

System > Logs > Configuration

This section allows the administrator to:

Define remote syslog destinations

Configure log publishers

Control which log types (system, audit, LTM, ASM, etc.) are forwarded to external syslog servers

Why the other options are incorrect:

A. System > Configuration > Local TrafficUsed for traffic management settings, not logging.

C. System > Logs > AuditDisplays audit log settings and content but does not configure remote syslog destinations.

D. System > Configuration > DeviceUsed for device-level settings such as hostname and platform configuration, not logging.

Therefore, the correct location to reconfigure BIG-IP to send logs to new syslog servers is System > Logs > Configuration.

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Comprehensive and Detailed Explanation From BIG-IP Administration20 Control Plane Administration documents: Connectivity management involves ensuring that the physical layer matches the networking environment. Interface properties, including media speed, duplex settings, and MTU, are managed at the Control Plane level under the Network menu. To resolve a mismatch with an upstream switch, the administrator must navigate to Network > Interfaces to manually override auto-negotiation settings.

On BIG-IP systems, SSH access restrictions are configured under the /sys sshd object. The allow property defines the IP addresses or networks permitted to connect to the management interface using SSH.

The list command is used to display the current configuration settings.

Therefore, tmsh list /sys sshd allow correctly displays the configured allowed IP ranges.

Why the other options are incorrect:

A (show) displays runtime or statistical information, not configuration values.

C and D incorrectly reference /etc/hosts.allow; BIG-IP manages SSH access through TMSH objects, not by directly listing host files in this context.

Comprehensive and Detailed Explanation From BIG-IP Administration Con10trol Plane Administration documents: Placing a device in the FORCED_OFFLINE state is a critical procedural concept for HA maintenance111213. 1415Unlike simply being 'Standby16', the FORCED_OFFLINE state ensures tha17t the Control Plane will not participate in failover selection, effectively preventing the device from becoming 'Active' even if the peer fails18. This state also allows the administrator to terminate existing connections to ensure no traffic is being processed during the maintenance window19.

Identifying the current device status includes knowing which software modules (such as LTM, ASM, or APM) are active and how much hardware resource (CPU/Memory) is allocated to them40404040. The System > Resource Provisioning screen displays the licensing status and allows the administrator to set the provisioning level (Nominal, Dedicated, or Minimum) for each module.

F5 Support uses a specific scale to categorize the urgency of technical issues, which helps the Control Plane management team prioritize resources effectively.

Severity 1 (Critical): Used for emergency situations where a production site is completely down, or there is a critical impact on business operations with no workaround available.

Severity 2 (High): Assigned when a system is severely degraded, or a primary function is significantly impacted, but the site remains operational in a degraded state.

Severity 3 (Medium): Applicable for issues where there is a partial loss of non-critical functionality, or the system is failing intermittently but the core business is not currently impacted.

Severity 4 (Low): This is the appropriate level for non-critical issues, general "how-to" questions, or maintenance planning. Since the administrator plans to resolve this issue in two weeks, it falls under the category of a low-priority maintenance task that does not require an immediate response from F5 support.

Reactivating a BIG-IP license is a traffic-disruptive operation. During the license reactivation process, the BIG-IP system performs a configuration reload, which results in a temporary interruption of all traffic processing. Because traffic handling is affected, F5 explicitly recommends scheduling license updates during a maintenance window.

This behavior is documented in F5 Knowledge Base articles, which state that license reactivation impacts traffic and must be planned accordingly during upgrades or system changes.

The other options are not considered disruptive:

Creating a QKView is primarily a diagnostic task and does not interrupt traffic.

Running tmsh save sys config only saves the running configuration to disk.

Generating a UCS is resource-intensive but does not reload configuration or interrupt traffic processing.

Managing how a BIG-IP communicates with external management services like Syslog is a core Control Plane task. The Configuration Utility organizes these settings under the "System" menu. Specifically, to define remote logging destinations and formats, the administrator must navigate to System > Logs > Configuration to ensure the Control Plane correctly forwards system events to external collectors

When BIG-IP is configured to use remote authentication (such as LDAP), all authentication and authorization attempts—including successes and failures—are logged to /var/log/secure.

For LDAP-based administrative login issues, /var/log/secure contains:

LDAP authentication failures

PAM authentication errors

Authorization and access-denied messages

Details explaining why a remote user could not log in

Why the other options are incorrect:

/var/log/user.log is not a standard BIG-IP log file for authentication.

/var/log/ltm logs traffic management events, not user authentication.

/var/log/messages contains general system messages but not detailed authentication failure information.

Therefore, the correct log file to troubleshoot LDAP administrative login failures is /var/log/secure.

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BIG-IP provides two supported and documented methods to manually force a device into standby state in a high-availability (HA) configuration:

CLI method (A):

tmsh run /sys failover device standby

This is the correct and supported TMSH command to force the local device to transition from active to standby.

Configuration Utility method (B):Navigating to Device Management > Devices > Local Device (Self) and selecting Force to Standby performs the same operation through the GUI and is fully supported.

Why the other options are incorrect:

C is incorrect: Traffic Groups do not provide a “Force to Standby” option for the local device; traffic groups are used to manage which device owns specific traffic, not to force device-level failover.

D is incorrect: tmsh run /sys failover standby is not a valid TMSH command. The correct syntax requires device standby.

Thus, the correct answers are A and B.

Comprehensive and Detailed Explanation From BIG-IP Administratio24n Control Plane Administration documents: TMOS Device Service Cluste25ring (DSC) allows for configuration changes to be made on any device within a synchronization group. If Auto-Sync is enabled, the Control Plane detects the change on the Standby unit and automatically propagates (pushes) that updated configuration to the other members of the HA pair

Traffic Groups are the mechanism BIG-IP uses to control which device owns specific application traffic in a high-availability (HA) configuration. When maintenance is required on a device that is currently active for a traffic group, the correct and recommended action is to fail over that traffic group to another device in the device group.

Failing over the traffic group moves ownership of that traffic group (and the virtual servers associated with it) to another available device without forcing the entire device into standby.

This allows targeted maintenance while minimizing impact to other traffic groups that may still be active on the device.

Why the other options are incorrect:

A is unnecessary and incorrect; traffic groups are not recreated for routine maintenance.

C forces the entire device to standby, which may move more traffic than intended.

D (Demote) affects device trust/priority behavior and is not the standard or recommended method for moving traffic group ownership.

Therefore, selecting the Traffic Group and choosing Failover is the correct solution.

Maintaining an accurate and synchronized clock across all members of a device group is a fundamental requir5ement for the BIG-IP Control P6lane to establis7h and maintain device tru8st9.

Time Delta Impact: As shown in the exhibit, the "Time Delta to Local Device (sec)" is 12.

Trust Mechanism: Device trust relies on secure certificate-based communication (SSL/TLS) . If the time difference between devices is too large (typically more than a few seconds), the Control Plane cannot validate the certificates, leading to a failure in the trust relationship .

ConfigSync Failure: When device trust is broken due to time drift, the systems cannot verify the identity of the peer, which directly prevents the ConfigSync process from executing on the affected device, such as bigip3.local in this scenario.

Resolution: Administrators must ensure that all devices in a high availability pair are configured to use the same reliable NTP servers to keep their system clocks aligned.

The correct command for restoring an encrypted UCS archive via the command line is D. load /sys ucs <</b>filepath> passphrase <</b>password>.