Exam F5CAB2 Topic 4 Question 25 Discussion
Actual exam question for F5's F5CAB2 exam
Question #: 25
Topic #: 4
Question #: 25
Topic #: 4
Active connections to pool members are unevenly distributed. The load balancing method is Least Connections (member). Priority Group Activation is disabled.
What is a potential cause of the uneven distribution? (Choose one answer)
What is a potential cause of the uneven distribution? (Choose one answer)
Suggested Answer: C Vote an answer
With Least Connections (member), BIG-IP attempts to send new connections to the pool member with the fewest current connections. In a perfectly "stateless" scenario (no affinity), this often trends toward a fairly even distribution over time.
However, persistence overrides load balancing:
* When a persistence profile is applied, BIG-IP will continue sending a client (or client group) to the same pool member based on the persistence record (cookie / source address / SSL session ID, etc.).
* This means even if another pool member has fewer connections, BIG-IP may still select the persisted member to honor session affinity.
* The result can be uneven active connection counts, even though the configured load balancing method is Least Connections.
Why the other options are not the best cause:
* A. Priority Group Activation is disabledPriority Group Activation only affects selection when priority groups are configured; disabling it does not inherently create uneven distribution under Least Connections.
* B. SSL Profile Server is appliedA server-side SSL profile affects encryption to pool members, but it does not by itself cause skewed selection across pool members. (Skew could happen indirectly if members have different performance/latency, but that's not the primary, expected exam answer.)
* D. Incorrect load balancing methodLeast Connections is a valid method and does not itself explain unevenness unless something is overriding it (like persistence) or pool members are not all eligible.
Conclusion:
A persistence profile is the most common and expected reason that active connections become unevenly distributed, because persistence takes precedence over the Least Connections load-balancing decision.
However, persistence overrides load balancing:
* When a persistence profile is applied, BIG-IP will continue sending a client (or client group) to the same pool member based on the persistence record (cookie / source address / SSL session ID, etc.).
* This means even if another pool member has fewer connections, BIG-IP may still select the persisted member to honor session affinity.
* The result can be uneven active connection counts, even though the configured load balancing method is Least Connections.
Why the other options are not the best cause:
* A. Priority Group Activation is disabledPriority Group Activation only affects selection when priority groups are configured; disabling it does not inherently create uneven distribution under Least Connections.
* B. SSL Profile Server is appliedA server-side SSL profile affects encryption to pool members, but it does not by itself cause skewed selection across pool members. (Skew could happen indirectly if members have different performance/latency, but that's not the primary, expected exam answer.)
* D. Incorrect load balancing methodLeast Connections is a valid method and does not itself explain unevenness unless something is overriding it (like persistence) or pool members are not all eligible.
Conclusion:
A persistence profile is the most common and expected reason that active connections become unevenly distributed, because persistence takes precedence over the Least Connections load-balancing decision.
by Murphy at Oct 05, 2026, 12:26 PM
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