F5 BIG-IP Administration Data Plane Configuration (F5CAB3) exam F5CAB3 Exam Dumps: Updated Questions & Answers (May 2026)

Fallback persistence is used when the primary persistence method fails. Source Address Affinity is a Layer 4 persistence method and is fully supported as a fallback option for most virtual server types.

BIG-IP provides several built-in TCP profiles optimized for different traffic patterns and network conditions. When attempting to improve general TCP performance, the recommended starting point is f5-tcp-progressive.

According to the BIG-IP Administration: Data Plane Configuration documentation:

f5-tcp-progressive is designed as a balanced, general-purpose TCP optimization profile.

It dynamically adjusts TCP behavior to improve throughput and latency for most enterprise applications.

It is the recommended first-choice profile when tuning TCP performance before moving to more specialized profiles.

Why the other options are incorrect:

A. f5-tcp-legacyThis profile exists for backward compatibility and does not include modern TCP optimizations.

C. f5-tcp-mobileThis profile is optimized specifically for high-latency, lossy mobile networks and is not suitable for general-purpose environments.

D. No optionBIG-IP explicitly provides built-in TCP profiles for performance tuning; using none would forgo optimization opportunities.

Correct Resolution:

The administrator should first apply f5-tcp-progressive to evaluate potential TCP performance improvements before considering more specialized profiles.

The X-Forwarded-For header preserves the original client IP when SNAT is enabled.

URI-based traffic steering requires inspection of the HTTP request. BIG-IP processes HTTP headers and URIs in the HTTP_REQUEST event. Pool member selection based on URI must occur before the request is sent to the server, making HTTP_REQUEST the correct event.

SSH is a TCP Layer 4 protocol. Applying an HTTP profile causes BIG-IP to expect HTTP headers, breaking SSH sessions. Removing the HTTP profile allows raw TCP forwarding.

Persistence overrides load balancing decisions by maintaining client-to-server affinity.

This scenario describes a classic case of asymmetric routing in a " one-arm " or non-gateway deployment. When a BIG-IP system is configured for SSL offloading, the following traffic flow occurs:

Client-Side: The client establishes a successful SSL/TLS handshake with the Virtual Server. This explains why the user can " successfully establish an SSL connection. "

Server-Side: The BIG-IP decrypts the traffic and forwards it as plain HTTP to the backend server. The packet trace confirms the server receives the HTTP GET request and responds with the content.

The Routing Failure: By default, the BIG-IP system preserves the client ' s original source IP address. If the backend server ' s default gateway is not the BIG-IP system (or if the server is on the same subnet as the client), the server will attempt to send the response directly back to the client ' s IP address, bypassing the BIG-IP.

Stateful Drop: Because the BIG-IP is a Full Proxy, it expects the response to return through its own internal state table to be encrypted and sent back to the client. Since the response bypasses the BIG-IP, the BIG-IP connection eventually times out, and the client receives no data despite the server having sent it.

Solution (SNAT): Enabling Secure Network Address Translation (SNAT), specifically SNAT Auto Map, ensures that the BIG-IP replaces the client ' s source IP with its own internal self-IP before sending the request to the server. This forces the server to send the response back to the BIG-IP, allowing the BIG-IP to complete the transaction and deliver the content to the user.

To determine if an iRule is influencing traffic for a specific Virtual Server, the administrator must verify the association between the Virtual Server object and any applied scripts. In the BIG-IP Configuration Utility (GUI), this association is found under the Resources tab of the specific Virtual Server. While there is an " iRules " sub-menu under Local Traffic, checking the Virtual Server ' s Resources tab is the definitive way to see which specific rules are currently active and in what order they are being processed for that particular traffic flow.

From the Command Line Interface (CLI), the tmsh list /ltm virtual < virtual_server > command provides a full text-based output of the virtual server ' s configuration. If iRules are applied, they will appear within a " rules { ... } " block in the command output. This is more effective than Option A, which only lists the contents of the iRule itself but does not show if or where it is applied. Option C is a common misconception; while some versions of the GUI have reorganized menus, the standard location for managing the association of profiles, policies, and iRules to a Virtual Server remains the " Resources " section. By identifying the applied iRule, an administrator can then review the script logic—often containing commands like pool or node—to see if it is overriding the default pool selection based on specific HTTP headers, URI paths, or client IP addresses.

In this scenario, each backend node (server) hosts multiple services and is referenced by multiple pools and virtual servers. The goal is to ensure an equal number of total connections per backend server, regardless of how many pool members (services/ports) exist on that server.

According to the BIG-IP Administration: Data Plane Configuration documentation:

Least Connections (node) tracks the total number of active connections to a node across all pool members and services.

This algorithm ensures load distribution is balanced at the server level, not just at the individual service (member) level.

It is specifically recommended when:

Multiple pool members exist on the same backend server

Multiple virtual servers reference the same backend servers

Why the other options are incorrect:

B. Predictive (member)Predictive algorithms are advanced and traffic-pattern based, but they operate at the member level and do not guarantee equal connections per server.

C. Least Connections (member)This balances connections per pool member, which can overload a server hosting multiple members while still appearing “balanced” per member.

D. Predictive (node)Although node-aware, predictive algorithms are less deterministic and not the best choice when strict equality of connections is required.

Correct Resolution:

Using Least Connections (node) ensures that each backend server carries an equal connection load across all services and pools.

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.