F5 F5CAB4 - BIG-IP Administration Control Plane Administration (F5CAB4) exam

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 <filepath> passphrase <password>.

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.

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.

===========

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.

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.

In netstat output:

0.0.0.0:443 means the service is bound to all available IPv4 interfaces on the system.

LISTEN indicates the service is actively waiting for incoming connection requests.

Therefore, this output confirms that a service (commonly HTTPS/443, such as the BIG-IP Configuration Utility or an application listener) is actively listening on all interfaces, making B the correct answer.

Why the other options are incorrect:

A would show 127.0.0.1:443 if it were loopback-only.

C is incorrect because LISTEN explicitly indicates readiness to accept connections.

D is unrelated; standby state does not affect socket binding shown by netstat.

Hence, the correct answer is B.

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.

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.

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)