Practice Free F5CAB5 BIG-IP Administration Support and Troubleshooting (F5CAB5) exam Exam Questions Answers With Explanation

Comprehensive and Detailed 150 to 250 Words Explanation From BIG-IP Administration, Support, and Troubleshooting Documents:

AQKViewfile is the primary diagnostic support bundle used by F5 Support to troubleshoot BIG-IP system issues. It contains comprehensive system information, including running configuration, licensing details, module provisioning, hardware status, software versions, log files, statistics, and the output of numerous diagnostic commands. Generating a QKView is a standard and recommended first step when investigating performance problems, configuration issues, or when opening a support case with F5.

In the BIG-IP Configuration Utility (GUI), the correct and supported location to generate a QKView isSystem > Support. This menu is specifically designed for support and troubleshooting operations. From this section, administrators can generate a QKView file, monitor its creation progress, download it locally, or upload it directly to F5 iHealth for automated analysis. This workflow is clearly documented in BIG-IP Administration and Support guides and aligns with F5 best practices.

The other menu options are not appropriate:

System > Configurationis used for system-wide settings such as DNS, NTP, and device identity.

System > Archiveis used to create UCS backup files, which are configuration backups, not diagnostic bundles.

System > Logsis used only for viewing system logs, not generating support files.

Therefore,System > Supportis the correct and only valid answer.

Before upgrading a BIG-IP system to a newer TMOS version, it is critical to review known issues to avoid introducing instability or regressions.F5 Bug Tracker (Option B)is a primary resource for this purpose. It allows administrators to search for documented software defects by TMOS version, module, symptom, or bug ID. Using Bug Tracker, an administrator can identify unresolvedissues, fixed bugs, and behavioral changes that may affect their specific deployment, such as traffic handling, high availability, or module-specific functionality. This directly supports proactive troubleshooting and informed upgrade planning.

F5 iHealth (Option D)is another essential tool used during upgrade preparation. iHealth analyzes uploaded UCS or QKView files and correlates the device configuration and software version with F5’s known issues database. It provides actionable reports highlighting critical defects, upgrade risks, interoperability concerns, and recommended target versions. iHealth is especially valuable because it contextualizes known issues based on the actual configuration running on the device.

The other options are not appropriate for verifying known software issues.F5 End User Diagnostics (Option A)is a client-side troubleshooting tool,F5 University (Option C)is a training platform, andF5 Downloads (Option E)is primarily used to obtain software images and release notes, not to analyze known defects in depth.

When a pool member is markedDOWN, it indicates that the configured health monitor is failing. The most effective troubleshooting approach is to focus on the monitor behavior and the actual traffic between BIG-IP and the pool member.

Enabling monitor logging (Option B)is a recommended first step. Monitor logging provides detailed information about why the health check is failing, such as timeouts, connection refusals, incorrect responses, or unexpected status codes. This directly correlates with BIG-IP troubleshooting best practices and allows administrators to confirm whether the failure is due to application behavior, incorrect monitor configuration, or network reachability.

Collecting a TCPdump packet capture (Option D)is also a highly effective method. A packet capture allows the administrator to verify whether the monitor probes are being sent, whether responses are received, and whether packets are being dropped, reset, or malformed. This is especially valuable when diagnosing firewall issues, SSL problems, or application-level failures.

Reviewing pool statistics (Option C) is useful for general monitoring but does not explainwhya health monitor is failing. Reviewing the routing table (Option A) is typically unnecessary unless there is evidence of a broader routing issue affecting multiple destinations.

Comprehensive and Detailed Explanation From BIG-IP Administration S73upport and Troubleshooting documents: Persistence is critical for ensuring that a client's session remains with the same pool member throughout its duration. If primary persistence (like Cookie Persistence) fails—for instance, because the client has disabled cookies—load balancing will not work as expected, and the session may be broken. A "Fallback Persistence Profile" provides a backup method75. The most common and reliable fallback method is "Source Address Affinity"76. This method tracks the client's IP address in the BIG-IP's persistence table and ensures that any subsequent requests from that IP are routed to the same pool member, even if the primary persistence token is missing. Troubleshooting session drops often involves checking if a fallback method is configured to handle scenarios where the primary method is unsupported by the client's browser or environment. Without a fallback, the BIG-IP would revert to standard load balancing, potentially sending the client to a different server that lacks their session data.

Comprehensive and Detailed Explanation From BIG-IP Administration Support and Troubleshooting documents: Monitoring resource utilization is essential for maintaining system stability. If the root (/) file system reaches 100% capacity, the BIG-IP may become unresponsive, fail to save configuration changes, or experience daemon crashes83. When the / partition is full, the immediate troubleshooting step is to identify large or unnecessary files—such as old log files, core dumps, or temporary installer files—located specifically within that file system84. In the provided exhibit, /dev/md4 is explicitly listed at 100% usage for the / mount point85. Checking other partitions like /usr (which is at 82% in the exhibit) would not resolve the immediate "Full" status of the root directory86. Administrators often use the du (disk usage) command via the CLI to find the problematic files. Managing disk space is a proactive task; however, when utilization hits 100%, it becomes a reactive troubleshooting emergency that must be resolved to restore the management plane's functionality.

When a BIG-IP device group shows aChanges Pendingstatus, it indicates that one or more devices in the group have configuration changes that have not yet been synchronized to the other members. To identifywhich device has the most recent (authoritative) configuration, the administrator must view the detailed synchronization status at thedevice group level.

The correct location isDevice Management > Device Groups (Option D). Within this menu, the BIG-IP Configuration Utility displays each device group along with its synchronization status and provides details about which device has pending changes. From this view, the administrator can clearly see which device is marked as havingchanges pending, making it the source device that should be used to initiate aSync to Groupoperation.

The other options do not provide the required level of detail:

Device Management > Overview (Option A)shows general HA status but not configuration ownership.

Device Management > Devices (Option B)lists devices but does not clearly identify which one holds unsynchronized changes.

System > High Availability (Option C)focuses on failover and traffic groups, not configuration sync state.

This workflow aligns with BIG-IP best practices for configuration synchronization and ensures changes are propagated correctly without overwriting newer configurations.

According toofficial F5 documentation (K52015891 – Troubleshooting BIG-IP power supply issues),hardware-related alerts for power supplies, fans, and chassis components are logged in /var/log/ltm.

When a BIG-IP device experiences a power supply issue—such as failure, intermittent outages, or fan-related faults—the system generates alerts through internal platform monitoring services. These alerts are written to the/var/log/ltmfile and often appear with messages similar to:

Chassis power supply 2 has experienced an issue. Status is as follows: FAN=bad; STATUS=bad.

This makes /var/log/ltm theauthoritative log filefor identifying and verifying power supply and chassis-related problems on BIG-IP systems.

The other log files are not appropriate for this purpose:

/var/log/daemon.logcontains general daemon messages but isnot the primary sourcefor chassis hardware alerts.

/var/log/kern.loglogs kernel-level events, not platform power status.

/var/log/auditrecords administrative actions and configuration changes.

Conclusion:

Per F5-supported guidance, when suspecting power supply outages or chassis hardware issues, the BIG-IP Administrator shouldalways check /var/log/ltm first.