F5 Networks F5CAB3 Exam Dumps

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

The BIG-IP Configuration Utility (GUI) organizes information hierarchically to allow for granular management of application objects. A Pool is a collection of backend servers (pool members) that provide the same service. To verify the specific network parameters---such as the IP address and the service port---of the servers within a pool, the administrator must navigate to the specific pool's configuration.

The standard procedural path to verify this is Local Traffic > Pools: Pool List, where the administrator selects the specific pool name. Once inside the pool's configuration, the Members tab displays a list of all IP addresses and service ports associated with that pool. Under the 'Service Port' column, the administrator can confirm if the member is listening on port 80 (HTTP).

Options A and B are incorrect for this specific verification task. While Nodes (Option A) show the health of a physical server, a node represents only an IP address and does not have a 'Service Port' associated with it until it is defined as a pool member. Verifying the Health Monitor (Option B) would tell the administrator how the system is checking the member's status, but it does not definitively show the port on which the member is actually receiving application traffic. In a BIG-IP environment, a pool member is uniquely identified by the combination of its Node IP and its Service Port, and the Members tab is the primary interface for managing and auditing these specific member attributes.

SSH is a Layer 4 TCP-based protocol that operates on TCP port 22 and does not use HTTP in any capacity. In the exhibit, the Virtual Server is configured with an HTTP Profile applied, which is inappropriate for SSH traffic and causes connection failures.

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

An HTTP profile must only be applied to Virtual Servers handling HTTP or HTTPS traffic.

When an HTTP profile is attached, BIG-IP expects HTTP headers and attempts to parse application-layer data.

Non-HTTP protocols such as SSH, FTP (control), SMTP, and other raw TCP services will fail if an HTTP profile is enabled.

Why the other options are incorrect:

A . Set Protocol to UDPSSH uses TCP, not UDP. Changing the protocol would break SSH entirely.

B . Set Source Address to 10.1.1.2The source address setting controls client access restrictions and is unrelated to protocol parsing issues.

C . Set Destination Address/Mask to 0.0.0.0/0The destination address is already valid for a specific SSH service and does not impact protocol handling.

Correct Resolution:

The BIG-IP Administrator should remove the HTTP Profile (set it to None) so the Virtual Server functions as a pure Layer 4 TCP service, allowing SSH connections to pass through successfully.

In BIG-IP systems, iRules influence traffic only when they are attached to a Virtual Server. If application traffic is being sent to nodes or pool members that are not defined in the pool, this typically indicates that an iRule is overriding the default load-balancing behavior by explicitly selecting a pool or node.

According to BIG-IP Administration: Data Plane Configuration and official F5 guidance:

iRules are associated with Virtual Servers, not directly with pools or nodes.

To determine whether an iRule is actively affecting traffic, the administrator must inspect the Virtual Server configuration.

Explanation of the correct answers:

B . Via the GUI at the Resources tab for the virtual serverThe Resources tab in the Configuration Utility displays all traffic-handling objects applied to the Virtual Server, including assigned iRules. This is the primary GUI location to verify whether an iRule is influencing data plane traffic.

C . Via TMSH with the list /ltm virtual <virtual_server> commandThis TMSH command displays the full Virtual Server configuration, including any iRules listed under the rules section. It is the authoritative CLI method to confirm iRule usage.

Why the other options are incorrect:

A . Via TMSH with the list /ltm rule <irule> commandThis command only shows the contents of an iRule and does not indicate whether the iRule is attached to or used by any Virtual Server.

D . Via the GUI at the iRule tab for the virtual serverBIG-IP does not provide a dedicated ''iRule'' tab on Virtual Servers. iRules are viewed and managed under the Resources tab.

Correct Conclusion:

To verify whether an iRule is responsible for unexpected node selection, the BIG-IP Administrator must examine the Virtual Server configuration, either through the Resources tab in the GUI or by using TMSH to list the Virtual Server configuration.

A 400 Bad Request response from an HTTP/1.1 web server is a definitive indicator that the HTTP request sent by the health monitor is missing a required Host header. In HTTP/1.1, the Host header is mandatory per RFC 7230. Web servers --- particularly those hosting named virtual hosts such as www.f5.com --- will reject any HTTP/1.1 request that omits the Host header, returning a 400 error, which the BIG-IP monitor interprets as a failed health check, marking all members DOWN.

The correct Send string must include:

The GET request line with HTTP/1.1 protocol declaration

A \r\n (carriage return + line feed) after the request line

The Host: www.f5.com header to satisfy HTTP/1.1 requirements

A \r\n after the Host header

Connection: Close header to instruct the server to close the connection after responding

A final \r\n\r\n to properly terminate the HTTP request headers

Only option C satisfies all these requirements with the correct syntax and Host header inclusion.

Option D (the current configured string) omits the Host header entirely --- the root cause of the 400 error. Options A and B are structurally incomplete or syntactically malformed.