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

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 .

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.

Managing the license is a primary Control Plane task required to activate software modules and features on a BIG-IP device.

License Management Utility : All actions related to the device license, including initial activation, renewal, and adding add-on keys, are performed under the System > License section of the Configuration Utility.

Procedural Requirements : Licensing often requires the generation of a " dossier, " which is a unique encrypted string used by the F5 License Server to generate the final license file.

Impact on Services : Updating or re-activating a license generally requires a restart of system services (such as the tmm daemon), which will temporarily disrupt traffic processing unless performed on a standby unit in a high availability pair.

Add-on Licenses : If an administrator needs to increase the capacity of a specific module (like increasing the SSL TPS limit or adding a new module like ASM), the new registration keys are entered through this same interface using the " Re-activate " button.

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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Audit logging is a specialized feature within TMOS designed to track administrative actions. According to F5 documentation, whenever a system object (like a virtual server, pool, or profile) is created, modified, or deleted, the system records the event. These logs are stored specifically in /var/log/audit. This is essential for control plane administration to track " who did what and when " regarding the device configuration.

On BIG-IP systems, all authentication attempts for administrative access—including logins to the Configuration Utility (GUI) —are logged in /var/log/secure . This log file records:

Successful and failed login attempts

The username used

The authentication method (local, LDAP, RADIUS, etc.)

Access denials and PAM authentication errors

Why the other options are incorrect:

/var/log/pam/tallylog tracks account lockouts and failed attempt counters, not detailed login attempts.

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

/var/log/httpd logs web server activity but does not record authentication success or failure for BIG-IP administrative users.

Therefore, the correct log file to verify whether a user attempted to log in to the BIG-IP Configuration Utility is /var/log/secure .

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This log message indicates that the system is low on memory and has activated ' Aggressive Mode ' to reclaim resources by closing old connections 37 . In an HA environment, one way to ensure state stability during memory pressure is to manage how connection data is handled 38 . While the document suggests D, procedural mitigation for ' Aggressive Mode ' often involves reviewing resource provisioning or optimizing connection idle timeouts to reduce memory footprint 39 .

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

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.

A QKView is a comprehensive snapshot of the device ' s Control Plane state, configuration, and logs used for troubleshooting. By default, the qkview utility stores its generated output file in the /var/tmp/ directory. Administrators must know this path to retrieve the file for upload to F5 iHealth or Support.

In a BIG-IP Device Service Cluster (DSC) , manual configuration synchronization is performed using the ConfigSync framework. The supported and documented command to manually push the local configuration to a specific device group is:

tmsh run cm config-sync to-group < device_group >

This command:

Initiates a one-time manual ConfigSync

Pushes the local device’s configuration to all members of the specified device group

Is commonly used when auto-sync is disabled or when the administrator wants explicit control over synchronization timing

Why the other options are incorrect:

A is not a valid TMSH command for ConfigSync.

B enables auto-sync but does not perform an immediate synchronization.

D is not a valid or supported TMSH command for device group configuration synchronization.

Therefore, the correct command to manually synchronize configuration to a device group is C .

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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

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 .

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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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.

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.

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 .

Monitoring and reporting current device status involves tracking the health of traffic objects like Virtual Servers 20 . The Control Plane logs transition events—such as a Virtual Server moving from ' Available ' (green) to ' Offline ' (red) due to health monitor failures—in the /var/log/ltm file 21212121 . While the audit log tracks who changed a configuration, the LTM log tracks system-initiated status changes 22222222 .