Pass the F5 F5-CA F5CAB5 Questions and answers with CertsForce

In complex network environments, "SNAT Automap" is frequently used to ensure that backend servers send return traffic through the BIG-IP. However, SNAT hides the original client's IP address, replacing it with the BIG-IP's self-IP. When interpreting traffic flow for security or logging purposes, backend servers often need that original IP. To resolve this without breaking the network-layer routing provided by SNAT, the administrator should apply an HTTP profile to the virtual server and enable the "Insert X-Forwarded-For" option. When this is enabled, the BIG-IP inserts a standard HTTP header containing the client's original IP address before forwarding the request to the pool member. This troubleshooting method allows the backend application to log the actual user's identity while maintaining a functional L3/L4 traffic flow where the server responds to the BIG-IP's local address. This is a standard troubleshooting solution for "web server not working as expected" scenarios where applica8tion logic depends on knowing the geography or specific identity of the connecting user.

This scenario describes a classic network performance issue known as the "Mega-Proxy" problem. When an organization routes all employee traffic through a single proxy server, the BIG-IP sees thousands of unique users as having the exact same source IP address. If the administrator has configured "Source Address Affinity" persistence, the BIG-IP will correctly follow the rule but incorrectly route all users to the same single backend pool member. This creates a severe load imbalance where one server is overwhelmed while others remain idle, leading to poor application response times. To resolve this, the administrator must change the persistence profile to "HTTP Cookie". Cookie-based persistence allows the BIG-IP to place a unique identifier in each user's browser, allowing the system to distinguish between individual sessions even if they share the same source IP. This fix ensures that traffic is distributed evenly across the pool members, restoring4 the expect5ed load balancing functionality and resolving the slow performance reported by users behind the corporate proxy.

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.

The pool member is markedDOWNbecause it is monitored bymultiple health monitors, specifically anHTTPmonitor and anHTTP/2monitor. The status message clearly shows that theHTTP monitor is UP, while theHTTP/2 monitor is DOWN. In BIG-IP, when multiple monitors are assigned to a pool member, the default behavior isAND logic, meaningall assigned monitors must succeedfor the pool member to be considered healthy.

In this scenario, the server is responding successfully to standard HTTP (likely HTTP/1.1) requests but does not support or respond correctly to HTTP/2 requests. As a result, the HTTP/2 monitor fails, which causes the overall monitor status to beDOWN, even though HTTP traffic itself is working.

This behavior is expected and documented in BIG-IP monitoring logic. Unless the monitor rule is explicitly changed to“at least one of”, a single failing monitor will mark the pool member down. Therefore, the correct conclusion is that the pool member isonly serving HTTP traffic, not HTTP/2.

The resolution would be to either remove the HTTP/2 monitor, correct the application to support HTTP/2, or adjust the monitor rule to match the intended health-check logic.

To collect application-layer details such asHTTP status codes(200, 404, 500, etc.) andHTTP methods(GET, POST, PUT, DELETE), the BIG-IP system must use a profile designed for traffic visibility and reporting rather than basic traffic handling. TheAnalytics profile (Option C)is the correct choice because it is specifically designed to collect, store, and present detailed statistics about HTTP and TCP traffic passing through a virtual server.

When an Analytics profile is attached to a virtual server, BIG-IP can record metrics such as HTTP response codes, request methods, URI paths, latency, throughput, and client-side/server-side performance data. These statistics are then accessible through the BIG-IP GUI underStatistics → Analytics, allowing administrators to validate application behavior and troubleshoot performance or functional issues.

TheHTTP profile (Option B)enables HTTP protocol awareness and features like header insertion and compression, but it does not provide historical or statistical reporting of HTTP methods and response codes.Request Adapt (Option A)is used for ICAP-based content adaptation, not visibility.Statistics (Option D)is not a standalone profile and does not provide HTTP-level insight.

Therefore, the Analytics profile is the only default profile that fulfills this requirement.

To successfully performSSL offload and re-encryptionon a BIG-IP system, the virtual server must be configured withboth a Client SSL profile and a Server SSL profile. The Client SSL profile enables BIG-IP to decrypt inbound HTTPS traffic from clients, while the Server SSL profile is required tore-encrypt traffic before forwarding it to the pool members.

From the exhibit, the virtual server has aClient SSL profile configured, which allows BIG-IP to accept HTTPS connections from clients. However, there isno Server SSL profile attached, meaning BIG-IP attempts to sendunencrypted HTTP trafficto pool members listening on HTTPS (port 443). This protocol mismatch causes the server-side SSL handshake to fail, resulting in users being unable to connect to the application.

This behavior is well documented in BIG-IP SSL troubleshooting guides: when backend servers expect HTTPS, a Server SSL profile is mandatory to establish a secure connection from BIG-IP to the pool members.

The other options are incorrect:

Removing the Client SSL profile (Option A) would break client-side HTTPS.

The server-side TCP profile (Option B) is unrelated to SSL encryption.

Forward Proxy (Option C) is only used for outbound SSL inspection scenarios.

Therefore, configuring anSSL Profile (Server)is the correct and required solution.

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.

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 physical network link (like Interface 1.1) reaches its maximum capacity, it creates a bottleneck that negatively impacts network-level performance. To overcome the physical limits of a single interface, BIG-IP administrators use "Trunking," which is the F5 term for Link Aggregation (often implemented via LACP). A trunk object bundles multiple physical interfaces into a single logical link. By creating a trunk with two or more interfaces, the BIG-IP can spread the traffic load across all members of the trunk, effectively doubling or tripling the available bandwidth for the associated VLANs. Beyond performance, troubleshooting redundancy often leads to the use of trunks; if one cable in a trunk fails, the others continue to carry traffic, preventing a complete outage. This is a superior solution to simply increasing MTU (which requires end-to-end support) or manually setting media speeds. In a high-availability environment, configuring trunks is a foundational troubleshooting and optimization step to ensure that traffic spikes do not result in packet loss due to link saturation.