Free F5 Networks F5CAB3 Exam Dumps May 2026

The log message ''Intercept exhaustion'' indicates that the BIG-IP system has exhausted the available source port translations for one or more SNAT addresses. This occurs when too many concurrent client connections are being translated through a limited number of SNAT IP addresses, and all ephemeral source ports (typically ~64,000 per SNAT IP) are in use.

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

Each SNAT IP address provides a finite number of available source ports.

When the number of concurrent connections exceeds the available port space, the BIG-IP logs an Intercept exhaustion error and new connections fail.

The recommended resolution is to increase the available SNAT resources by adding additional IP addresses to the SNAT pool.

Why the other options are incorrect:

A . Increase the timeout of the SNAT addressesIncreasing timeouts may actually worsen the problem by keeping ports allocated longer, accelerating port exhaustion.

B . Remove the SNAT pool and apply SNAT AutomapSNAT Automap uses the Self IP addresses on the egress VLAN, which may not provide additional capacity and can introduce routing or design issues. This is not a direct or recommended fix for SNAT exhaustion.

C . Remove an IP address from the SNAT poolThis would reduce the number of available source ports and further exacerbate the intercept exhaustion condition.

Correct Resolution:

By adding an IP address to the SNAT pool, the BIG-IP increases the total number of available source ports, alleviating intercept exhaustion and restoring successful client connections.

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.