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

This scenario describes a classic routing issue often encountered during SSL offload deployments. The fact that an SSL connection is established indicates the Client SSL profile is working correctly. The packet trace showing the server " receives and responds " to the request is the most critical diagnostic clue.

When a BIG-IP receives traffic, it typically passes the client ' s original source IP address to the backend server. If the backend server ' s default gateway is not the BIG-IP (a common " one-arm " network topology), the server will attempt to send its response directly back to the client ' s IP via its own default router. The client ' s browser will reject this response because it expects traffic to come from the Virtual Server ' s IP, not the backend server ' s IP.

To resolve this, the administrator must enable SNAT (Source Address Translation), typically using SNAT Automap. When SNAT is enabled, the BIG-IP replaces the client ' s original source IP with one of its own Self IPs before forwarding the request to the server. Because the source of the packet is now the BIG-IP, the backend server is forced to send its response back to the BIG-IP. The BIG-IP then receives the response, translates it back, and delivers the content to the user. Option A is unnecessary if the servers are expecting plain-text traffic after the BIG-IP performs offload. Option D would only worsen the existing routing discrepancy.

When a single IP address (Virtual Server) must host multiple hostnames (e.g., site1.com, site2.com) over HTTPS, the BIG-IP must be able to present the correct SSL certificate for each site during the initial handshake. This requirement is handled by a technology called Server Name Indication (SNI).

To implement this on the BIG-IP, the administrator must use a Client SSL profile because the encryption is occurring between the user (Client) and the Virtual Server. Within the Client SSL profile settings, there is a field called Server Name. By creating multiple Client SSL profiles—each with a different " Server Name " (the hostname) and its corresponding certificate—and attaching them all to the same Virtual Server, the BIG-IP can inspect the SNI extension in the client ' s " Client Hello " packet. It then selects the specific profile that matches the requested hostname.

Option A is incorrect because " Client Name " is not the standard field name used for SNI hostname matching in the profile. Options B and C refer to Server SSL profiles, which manage the connection between the BIG-IP and the backend servers. While Server SSL profiles also have a " Server Name " field (used to send SNI to a backend server), the requirement here is to provide encrypted communication for " users " accessing the virtual server, which definitively requires a Client-side SSL configuration.

The requirement states that load balancing decisions must be based on the number of active connections on each pool member. This directly maps to the Least Connections (member) load balancing method.

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

Least Connections (member) selects the pool member with the fewest active connections at the time of the request.

This method dynamically adapts to real-time traffic patterns and ensures that more heavily loaded pool members receive fewer new connections.

It is especially effective for web servers where connection duration may vary and equal distribution of active sessions is desired.

Why the other options are incorrect:

B. Round RobinDistributes connections sequentially without considering current load or active connections.

C. Ratio (member)Distributes traffic based on static ratios, not real-time connection counts.

D. Ratio (node)Uses predefined ratios at the node level and does not account for active connection counts.

Correct Resolution:

Using Least Connections (member) ensures that new connections are directed to the pool member currently handling the fewest active connections, meeting the stated requirement.

This question addresses the critical architectural distinction between " member-based " and " node-based " load balancing in environments where servers are multi-homed or host multiple virtualized services. On a BIG-IP, a node represents the underlying IP address of a physical or virtual server, while a pool member represents a specific combination of that IP and a service port (e.g., 10.1.1.10:80).

When multiple pools reference the same IP address across different ports or Virtual Servers, using Least Connections (member) (Option D) only balances connections relative to that specific pool. For example, if Pool_A and Pool_B both use Server_X, and Pool_A has 100 connections while Pool_B has only 5, a member-based algorithm for Pool_B only sees the 5 connections and may continue to send traffic there even if Server_X is CPU-saturated by Pool_A.

The Least Connections (node) algorithm (Option B) solves this by tracking the aggregate total of all active connections directed to that specific node (IP address) across every pool on the system. By selecting the node with the absolute lowest total connection count, the BIG-IP ensures a more equitable distribution of work at the hardware resource level. Predictive methods (Options A and C) use a ranking system based on the trend of connection counts over time, but for the specific requirement of maintaining an equal number of current connections on multi-service servers, the direct Least Connections (node) calculation is the standard and most effective procedural choice.

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 c onsistently 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.

A red diamond indicates the Virtual Server is enabled but unavailable due to all pool members being down.

The Local Traffic > Network Map provides a single consolidated view within the BIG-IP Configuration Utility that displays the full relationship hierarchy of all application delivery objects simultaneously. This includes Virtual Servers, their associated Pools, individual Pool Members, applied iRules, profiles, and the health status of each object — all rendered in a single topological screen.

This view is specifically designed for administrators and users who need rapid situational awareness across the data plane without navigating multiple menu screens. Each object is colour-coded to reflect its current availability state (green = available, red = unavailable, yellow = degraded).

The alternative options do not satisfy all requirements:

Local Traffic > Monitors only displays health monitor configurations, not virtual server or pool member relationships.

Statistics provides performance counters and throughput data, not object relationship mapping.

Local Traffic > Virtual Servers lists virtual server configurations individually but does not provide a unified topology view inclusive of pool members and iRules in a single screen.

The Network Map is the authoritative single-pane-of-glass tool for application object visibility on BIG-IP.

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.