F5CAB4 BIG-IP Administration Control Plane Administration (F5CAB4) exam Questions and Answers

Although /var/log/ltm is primarily associated with Local Traffic Manager events, it is also the primary destination for system-level alerts generated by the Control Plane ' s chmand (Chassis Manager Daemon). Hardware status changes, including power supply failures, fan speeds, and temperature warnings, are logged as " notice " or " critical " events within the LTM log file.

When restoring a UCS file to replacement hardware (RMA device) , the license from the original device is not valid on the new system. If the UCS restore attempts to load the old license, BIG-IP reports license errors such as “License is not operational” , which can prevent traffic objects (including pools and virtual servers) from loading correctly.

To avoid this issue, F5 documentation recommends restoring the UCS without the license , using the following command:

tmsh load /sys ucs < ucs filename > no-license

This approach:

Restores all configuration objects (LTM, networking, certificates, keys, etc.)

Excludes the invalid license tied to the old hardware

Allows the administrator to activate a new license separately on the replacement device

Why the other options are incorrect:

A. Remove the license information from the UCS archive Not supported or recommended; UCS files should not be manually modified.

B. Revoke the license prior to restoring License revocation does not prevent the UCS from attempting to load license data.

D. Reactivate the license on the new device using the manual activation method This must be done after restoring the UCS and does not prevent the restore failure itself.

Therefore, the correct and supported method to avoid this error is C .

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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

On a BIG-IP system, NTP (Network Time Protocol) configuration is part of the system-level configuration settings . In the Configuration Utility, NTP servers are configured under the System configuration hierarchy .

The correct navigation path is:

System > Configuration > Device > NTP

This location allows the administrator to:

Add, modify, or remove NTP servers

Ensure accurate system time synchronization

Maintain proper time alignment required for features such as ConfigSync , HA failover , logging, and certificate validation

Why the other options are incorrect:

A. System > Platform is used for hardware-related settings.

B. System > Preferences manages UI and user preferences.

C. System > Services controls system daemons and services, not time configuration.

Therefore, the correct answer is D. System > Configuration .

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On BIG-IP systems, Local Traffic Manager (LTM) is responsible for:

Pool and pool member management

Health monitor execution

Marking pool members UP or DOWN based on monitor results

Events related to health monitor status changes , including when pool members transition between UP and DOWN , are logged in /var/log/ltm .

Why the other options are incorrect:

/var/log/audit records administrative configuration changes, not runtime health status.

/var/log/secure logs authentication and authorization events.

/var/log/monitors is not a standard BIG-IP log file.

Therefore, the correct log file for pool member health monitor status events is /var/log/ltm .

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BIG-IP supports remote authentication by integrating with centralized authentication services through its AAA framework. The supported and commonly used remote authentication servers include:

LDAP (A) Used to authenticate users against directory services such as Active Directory or other LDAP-compliant directories.

RADIUS (C) Commonly used for centralized authentication, authorization, and accounting, especially in network and security environments.

Why the other options are incorrect:

OAUTH (B) is an authorization framework, not supported as a direct administrative authentication backend for BIG-IP management access.

SAML (D) is primarily used for single sign-on (SSO) in application authentication scenarios, not for BIG-IP administrative login authentication.

Thus, the correct remote authentication server types are LDAP and RADIUS .

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.

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 host 494949494949494949 . This is essential for identifying potential " Aggressive Mode " triggers or hardware performance bottlenecks 50 .

watch-devicegroup-device shows (among other columns) the commit ID (cid.id / shown here as clu_id), the originating device for that commit (cid-orig / shown here as cl_orig), and the time the configuration change was made (cid.time / shown here as cl_time). The highest/newest commit ID and its time represent the most recent configuration change seen among the devices. ( clouddocs.f5.com )

bigip_a has the latest configuration (A) because it shows commit ID 3273 at 14:27:00 , which is newer than commit ID 1745 at 13:52:34 on bigip_b and bigip_c. ( clouddocs.f5.com )

Two devices are out of date (B) because bigip_b and bigip_c are still on the older commit ID 1745 , so they do not match the latest commit shown on bigip_a. ( clouddocs.f5.com )

Why the other options are not supported by this output:

C is not supported : bigip_c is not showing a newer commit than the others; it’s on the older commit (1745), so it’s not the source of the most recent change. The output’s cid-orig column is what tells you where the change was made. ( clouddocs.f5.com )

D/E are incorrect logic : matching cid.time between two devices only indicates they share the same change timestamp/commit , not that it is the correct or latest configuration. The “latest” is indicated by the newest commit ID/time (here, bigip_a). ( clouddocs.f5.com )

When a BIG-IP Administrator changes module provisioning (for example, enabling ASM on a system previously provisioned only for LTM ), the BIG-IP system must restart the Traffic Management Microkernel (TMM) process.

The TMM process is responsible for:

Traffic handling

LTM, ASM, and other traffic-processing modules

Enforcing security and application policies

Provisioning changes affect how traffic modules are loaded and integrated into TMM. As a result, TMM is restarted , which causes a temporary interruption of traffic processing . This is expected behavior and is why module provisioning changes should be planned during a maintenance window .

Why the other options are incorrect:

A. bd is related to blade/platform management, not module provisioning.

C. sshd handles SSH access and is not affected by provisioning changes.

D. httpd supports the Configuration Utility (GUI) and does not restart due to module provisioning.

Therefore, the correct answer is B. tmm .

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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 .

On BIG-IP systems that participate in a Device Service Cluster (DSC), each device compares the remote device’s system time to its own system time. If the difference is outside the ConfigSync time threshold (commonly referenced as 3 seconds by default ), BIG-IP updates the shell prompt to show “Peer Time Out of Sync” , and ConfigSync operations may fail until time is corrected (typically by fixing NTP reachability/configuration, or in some cases adjusting the threshold). ( cdn.studio.f5.com )

This message is specifically about time drift between peers in the trust domain/DSC—not basic reachability (so B is not what it means), and it does not prove which side is “correct” (so C is too specific). It also doesn’t directly mean an NTP source is “skewed” (A can be a cause , but the prompt message itself indicates the peer-to-peer time mismatch condition). ( cdn.studio.f5.com )

The recommended and supported method for creating BIG-IP users from the CLI is through TMSH , using the authentication subsystem.

tmsh create auth user < username > prompt-for-password:

Properly creates the user within BIG-IP’s AAA/authentication framework

Encrypts the password securely

Ensures the user is stored and managed correctly in the BIG-IP configuration database

Is fully supported and documented

Why the other options are incorrect:

B is unsafe and unsupported because editing bigip.conf directly and storing clear-text passwords violates security and configuration management best practices.

C (f5adduser / f5passwd) is deprecated and not recommended for modern BIG-IP versions.

D creates a Linux system user only , not a BIG-IP administrative user, and will not allow access to the Configuration Utility or TMSH roles.

On BIG-IP systems, authentication and authorization events are logged in /var/log/secure . This includes:

Successful and failed SSH login attempts

Invalid user authentication attempts

PAM (Pluggable Authentication Module) authentication failures

Access denials related to secure services

Why the other options are incorrect:

/var/log/messages contains general system messages and service events, not detailed authentication failures.

/var/log/audit records administrative configuration changes (who changed what and when), not login attempts.

/var/log/ltm logs traffic-management (TMM) and application-related events.

Therefore, the correct log file for investigating unauthorized SSH login attempts is /var/log/secure .

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For an issue involving an HTTP virtual server, the first log file to check is /var/log/ltm . A BIG-IP virtual server is an LTM traffic-management object, and runtime events related to virtual servers, pools, pool members, monitors, availability changes, and traffic-management behavior are normally written to the LTM log. /var/log/httpd/httpd_errors is not the correct first choice because it relates to the BIG-IP Configuration Utility web service, not to an HTTP application virtual server processing client traffic. /var/log/audit records administrative configuration changes, such as who modified an object and when. /var/log/messages contains broader system-level messages but is not the primary LTM troubleshooting log. Therefore, when the problem statement specifically says an HTTP virtual server is having an issue, the control-plane troubleshooting path starts with /var/log/ltm .

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When troubleshooting a BIG-IP system where a partition is reported as full (100% utilization), identifying and removing large or unnecessary files is the immediate next step for restoration of system stability.

Symptoms of Full Partitions : If a file system (such as the root / or /var) becomes full, it can result in unpredictable system behavior, failure to save configurations, and the inability to log in to the Web UI.

The Root (/) Partition : This partition is intentionally kept small on F5 systems. It is highly sensitive to the storage of third-party software or diagnostic files that should ideally be stored in the /shared or /var directories.

Procedural Resolution : To resolve 100% disk usage, administrators should check for large files on the affected partition using CLI commands like du -ah or find / -xdev -type f -exec du {} \; | sort -rn | head -20.

Common Culprits : Large files typically causing these issues include old core files, tech support bundles, large diagnostic logs (packet diags), or temporary files created during administrative tasks.

Diagnostics vs. Remediation : While tests like the EUD (End User Diagnostics) or platform diagnostics are useful for hardware verification, they do not resolve file system exhaustion issues that have already reached a critical 100% state.

Comprehensive and Detailed Exp11lanation From BIG-IP Administration Control Plane Administration documents: Monitoring specific object health is a core function of the Control Plane. While the dashbo12ard provides a global overview, granular per13formance data—such as the CPU overhead a specific Virtual Server is placing on the Traffic Management Microkernel (TMM)—is found under the Module Statistics. Navigating to Statistics > Module Statistics > Local Traffic > Virtual Servers allows an administrator to report on the current status and resource consumption of individual traffic objects.

To determine the current failover (HA) status of a BIG-IP system using tmsh, F5 documentation explicitly states that the administrator should use the following command:

show /cm failover-status

This command displays:

The current failover state (active, standby, or offline)

Detailed failover status information

The operational HA condition of the device within a device group

According to F5 Knowledge Base Article K08452454, the documented procedure for checking failover status is:

Log in to the TMOS Shell (tmsh)

Run show /cm failover-status

Why the other options are incorrect:

A. list /cm failover shows configuration settings, not operational HA status.

B. show /sys failover is not the documented command for checking current failover status and does not align with F5’s recommended procedure.