WithLeast 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 apersistence profileis applied, BIG-IP will continue sending a client (or client group) to thesame pool memberbased 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 beuneven 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:
Apersistence profileis the most common and expected reason that active connections becomeunevenly distributed, because persistencetakes precedence overthe Least Connections load-balancing decision.