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

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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Comprehensive and Detailed Explanation From BIG-IP Administration Control Plane Admi13nistration documents:

To accurately report the current status of specific web applications hosted on the same server (node), the Control Plane must use a monitor that operates at the application layer.

Application-Specific Monitoring: While a node (the IP address) might be up and responding to ICMP (ping) or TCP handshakes, a specific web service or path on that server could be failing.

Custom Send Strings: An HTTP monitor allows the administrator to define a "Send String" to request a specific page or URI related to the application in that pool .

Receive Strings: The "Receive String" identifies a unique value that the application must return to be considered "Available" .

Granular Status Reporting: By deploying these monitors at the pool level, the Control Plane can mark a pool member "Offline" for one application pool if the receive string is missing, while keeping it "Available" in another pool where the service is still healthy.

The User Configuration Set (UCS) is a flexible tool designed by the Control Plane to handle various lifecycle management scenarios, including upgrades and hardware migrations.

Version Compatibility (Option B): TMOS is designed to be backward compatible. The Control Plane can ingest a UCS file created on an older version of software and automatically upgrade the configuration objects to match the current, later version during the restore process.

Platform Portability (Option C): While a UCS archive contains platform-specific information, the BIG-IP system allows for "platform-independent" restores. This is a vital procedural concept for migrating from one hardware model to another or from physical hardware to a Virtual Edition (VE).

Management of State: When restoring to a different platform or a later version, the administrator often uses specific flags (such as no-license or platform-migrate in later versions) to ensure that only the portable configuration data is applied while preserving the new platform's unique identifiers.

The Statistics Dashboard is the primary graphical interface used by administrators to monitor the real-time performance and health of the BIG-IP system.

System-Wide Overview: Navigating to Statistics > Dashboard provides a centralized view of critical system-level metrics, including global CPU utilization (across all TMM instances and the Linux host) and total memory usage.

Performance Tracking: In addition to CPU and memory, the dashboard displays other vital statistics such as total active connections, throughput (bits/packets per second), SSL transactions per second (TPS), and compression efficiency.

Operational Health: Monitoring these metrics from the dashboard allows the administrator to quickly identify performance trends or resource exhaustion that could impact the Control Plane or Data Plane stability.

Comparison to Other Menus:

Local Traffic > Virtual Servers: Provides statistics specific to traffic objects rather than global system resources.

Network > Interfaces: Shows physical layer statistics like link status, errors, and drops for specific ports.

Device Management > Overview: Focuses on high availability (HA) states, synchronization status, and device trust rather than granular performance metrics.

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.

In the BIG-IP Configuration Utility, all system backup and restore operations—including UCS (User Configuration Set) file restoration—are performed from the Archives section.

The correct navigation path is:

System > Archives

From this location, the administrator can:

Upload UCS files

Restore UCS backups

Manage system archive files used for backup and recovery

Why the other options are incorrect:

A. System > Configuration is used for general system settings, not backup restoration.

C. Local Traffic > Virtual Servers is used for application traffic objects.

D. Local Traffic > Policies manages traffic policies, not system backups.

Therefore, the correct section to restore a UCS file using the Configuration Utility is System > Archives.

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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.

Restoring system states from backups is a fundamental Control Plane administrative task2. When a User Configuration Set (UCS) archive is created with encryption, it requires the correct passphrase to be decrypted and loaded during the restoration process.

UCS Command Structure: The tmsh load /sys ucs command is the specific utility for restoring these comprehensive configuration archives.

Encrypted Restores: If the archive was encrypted during creation, the passphrase argument must be appended to the command followed by the actual password used to encrypt the file.

Comparison with Other Options:

load /sys config file is used for loading text-based configuration files (like bigip.conf), not full UCS archives6.

The no-license flag is used when you want to restore a configuration without overwriting the existing license (common during RMA replacements), but it does not provide the mechanism for entering an encryption passphrase.

In a High Availability pair, the "Force to Standby" action is a Control Plane command used to trigger a manual failover. This option is only logical and available on the device that is currently in the Active state. If the button is greyed out, it indicates that the administrator is already logged into the Standby unit, which has no active traffic groups to relinquish.

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.

In F5 TMOS, administrative roles and user permissions are partition-specific. The User Manager role allows an account to manage other user accounts, but this authority is restricted to the administrative partitions to which the User Manager has been granted access.

Partition Awareness: If User1 (the User Manager) attempts to modify User2 and fails, while the full Administrator succeeds, it indicates that User2 resides in a partition where User1 does not have management rights.

Principle of Least Privilege: This principle dictates that a user should be given only the minimum level of access necessary to perform their job functions.

Procedural Solution: Granting "Administrator" privileges (Option B) would violate least privilege by giving User1 full control over all system settings and all partitions. Moving users between partitions (Options A and C) might disrupt the organizational security structure. The correct and most secure administrative action is to modify the partition access for User1 to include the partition where User2 is located. This enables User1 to manage User2’s properties while maintaining their restricted role as a User Manager.

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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Management of the device's identity and primary out-of-band connectivity is a central Control Plane responsibility.

Platform Settings: The System > Platform section of the Configuration Utility is used to manage global hardware and system parameters, including the hostname, management IP address, and time zone.

Management vs. Data Plane: It is critical to distinguish between the management interface and TMM data interfaces. While data plane IPs (Self IPs) are configured under Network > Self IPs, the dedicated management port settings are grouped with other platform-level configurations.

Access Control: This area is also used to manage administrative security, such as restricting SSH or HTTPS access to specific management subnets or IP addresses.

Impact of Change: Changing the management IP will immediately disconnect any active GUI or SSH sessions using the current management IP. The administrator must reconnect using the newly assigned address.

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 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)

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.

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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