F5CAB3 Exam Dumps : BIG-IP Administration Data Plane Configuration (F5CAB3) exam

SNAT Automap is a common configuration that replaces the client's original source IP address with one of the BIG-IP's self IP addresses. This ensures that the backend servers send return traffic back through the BIG-IP, which is necessary for the ADC to process the traffic correctly. However, a side effect of SNAT is that the backend servers only see the BIG-IP's IP in their logs, losing visibility into the true identity of the client.

To resolve this while still using SNAT for routing purposes, the administrator must configure the BIG-IP to "pass" the client's IP address at the application layer. This is achieved by using an HTTP Profile with the Insert X-Forwarded-For setting enabled. When this profile is applied to the Virtual Server, the BIG-IP intercepts the HTTP request, adds a header (X-Forwarded-For) containing the client's original IP, and then forwards the modified request to the server. The backend web server can then be configured to read this header and log the original client IP instead of the BIG-IP's SNAT address.

Other options are incorrect for this requirement. Performance (HTTP) (Option A) is a virtual server type optimized for speed but often lacks the full Layer 7 header manipulation capabilities of a Standard Virtual Server. SNAT Pool with the client IP (Option C) is technically impossible as SNAT pools use static, pre-defined IPs. There is no such thing as an HTTP Transparent profile (Option D) in standard BIG-IP administration for this purpose. The X-Forwarded-For header insertion within the HTTP profile is the standard procedural method for maintaining client visibility in SNAT-enabled environments.

The issue of "lost shopping carts" in an ecommerce environment is a classic symptom of a missing or improperly configured Persistence Profile. In modern web applications, session data—such as items added to a cart—is often stored locally on the specific web server that initially handled the user's request. If the BIG-IP system load balances a user's subsequent request (like clicking "Checkout") to a different server among the 50 webservers, the new server will not have the session data, and the user will appear to have an empty cart.

While Least Connections (node) is an efficient load balancing algorithm, it makes a new decision for every connection unless persistence is enabled. To resolve this, the administrator must implement a persistence mechanism. HTTP Cookie Persistence (Option A) is the industry standard for web applications. By assigning a cookie persistence profile to the Virtual Server, the BIG-IP inserts a unique cookie into the HTTP response. When the user's browser returns that cookie in future requests, the BIG-IP identifies the specific server that handled the first request and consistently directs the user back to that same server for the duration of their session.

Sip_info (Option B) is a persistence method for VOIP traffic and is not applicable to web traffic. Ratio load balancing (Options C and D) merely changes the distribution frequency but still does not guarantee that a specific user will stay on the same server across multiple requests. Therefore, adding a cookie persistence profile is the direct procedural fix to maintain session state and ensure ecommerce functionality.

In BIG-IP configuration, health monitors can be applied at three distinct levels: the node, the pool, or the individual pool member. To ensure that a specific application service—in this case, a database service on port 1521—is functioning correctly for the entire pool, the administrator should apply the monitor at the pool level. Navigating to Local Traffic > Pools > DB.Pool > Properties allows the administrator to select one or more monitors from the "Available" list and move them to the "Active" list.

Applying a monitor at the pool property level ensures that the BIG-IP checks the health of every member assigned to that pool using the same logic. If a database-specific monitor (such as a TCP handshake or an Oracle/SQL check) fails for a specific member, the BIG-IP marks that member as "offline" for that specific pool, preventing new connections from being sent to it. While monitors can be applied to Pool Members (Option D) to give different members unique monitoring logic, it is more administratively efficient to apply it to the pool properties when all servers are expected to behave identically. Applying it to Nodes (Option C) would only verify that the IP address is up (typically via ICMP), which does not guarantee that the database service on port 1521 is actually responding. Finally, Profiles (Option A) are used to define how traffic is handled once it is accepted by a Virtual Server, not for the proactive health checking of backend resources. Therefore, the pool properties page is the standard location for configuring service-specific availability requirements.