In which two slots should an administrator install additional RAM in a server with available slots: A2, A3, A4, B2, B3, and B4?

Selecting the two slots A2 and B2 for installing additional RAM is the correct approach because it exploits the dual-channel architecture commonly used in servers and motherboards. This architecture allows for increased memory throughput by accessing two RAM modules in parallel, effectively doubling the data paths for the memory.

In many server configurations, memory modules should be populated in a way that each channel has similar capacities. Here, A1 and B1 refer to the same channel, and A2 and B2 represent the second segment of these channels. By installing memory in A2 and B2, the server can access the RAM simultaneously across both channels, improving overall memory performance due to increased bandwidth.

Other slot combinations may not provide the same level of performance benefits. For instance, using A2 and A3 would not maximize the dual-channel capability since both slots are part of the same memory channel. Similarly, A2 and B4 or even B2 and B3 might not create an optimal setup, as these combinations could lead to unbalanced channel utilization, reducing data transfer efficiencies. Thus, the decision to place RAM in slots A2 and B2 is optimal for performance enhancement while ensuring compatibility and stability within the server architecture.