F5 F5CAB3 - BIG-IP Administration Data Plane Configuration (F5CAB3) exam

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

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.

Connection rate limits restrict how many new connections are accepted per second, protecting application resources.

When a pool contains servers with heterogeneous hardware capabilities (differing CPU, RAM, or connection limits), a static load balancing method like Round Robin is ineffective because it distributes requests equally, regardless of the server ' s capacity. To optimize traffic distribution for newer, more powerful servers, a dynamic or weighted method is required.

Weighted Least Connections (member): This is the ideal method for this scenario. It combines two factors:

Least Connections: It first checks the current active connection count to ensure traffic goes to the least busy server.

Weight (Ratio): It allows the administrator to assign a " Ratio " value to each pool member. Newer servers can be assigned a higher ratio (e.g., 3) while older servers are assigned a lower ratio (e.g., 1). The BIG-IP system uses these weights to disproportionately favor the newer servers even when connection counts are similar.

Why other options are incorrect:

Global Availability: This is primarily a GSLB (Global Server Load Balancing) or specific LTM priority group concept where traffic is sent to the first available member in a list until it fails, then moves to the next. It does not load balance based on capacity.

Round Robin: This passes each new connection request to the next server in line, treating the old and new servers exactly the same.

Least Connections (member): While this sends traffic to the server with the fewest active connections, it assumes all servers are equal. If an old server and a new server both have 10 connections, they are treated as equally capable of taking the 11th, which is not true in this scenario.

The configuration error is the HTTP Profile = http setting. The virtual server is intended to load balance SSH , which operates over TCP port 22 and is not an HTTP application protocol. The configured TCP protocol and TCP profile are therefore appropriate, but an HTTP profile should not be attached to this SSH virtual server.

F5 documentation states that an HTTP profile defines how BIG-IP manages HTTP traffic . The standard http profile operates in Reverse proxy mode by default and invokes BIG-IP ' s HTTP protocol processing. F5 separately documents Transparent HTTP proxy mode as the mode that can forward invalid HTTP traffic instead of dropping it. This distinction is important because an SSH protocol exchange is not syntactically valid HTTP traffic.

Setting HTTP Profile to None removes unnecessary Layer 7 HTTP parsing and leaves the virtual server handling the SSH connection through its TCP profile. The other changes are inappropriate: SSH requires TCP rather than UDP; the source address does not need to equal the virtual server ' s destination IP; and changing the destination to 0.0.0.0/0 is unrelated to the application-protocol mismatch.

Reference Topics: Local Traffic Profiles → HTTP Profiles , Proxy Mode , TCP profiles , Virtual Server profile assignment .