In which situation do you need to select switches with a back-front (BF) airflow?

Question

Options

• AThe switches are core switches in a dedicated rack with their ports facing the cold aisle
• BThe switches are ToR switches which will have the port side facing the opposite way as server
• CThe switches are middle of the rack switches with their ports facing the cold aisle
• DThe switches are ToR switches which will have the port side facing the same way as server ports

• A
  5% (1)
• C
  5% (1)
• D
  90% (18)

Explanation

Option D is correct because server network ports (NICs) are located at the back of the server, facing the hot aisle. When a ToR switch has its port side facing the same direction as server ports, those switch ports also face the hot aisle. To maintain proper hot-aisle/cold-aisle separation, the switch must use Back-to-Front (BF) airflow - drawing cool air in from the cold-aisle side (the switch's non-port "back") and exhausting heat out through the port side into the hot aisle.

Why the distractors are wrong:

• A & C both describe switches with ports facing the cold aisle. When ports face the cold aisle, cool air naturally enters at the port side and exits the rear - that's Front-to-Back (FB), not BF.
• B describes switch ports facing the opposite direction from server ports. Since server ports face the hot aisle, "opposite" means the switch ports face the cold aisle - again requiring FB airflow, not BF.

Memory tip: Think "same side = same heat problem." When the switch ports are on the same side as server ports (hot aisle), both devices exhaust heat the same way - you need BF to push that heat out through the port side into the hot aisle. A quick phrase: "Hot ports = BF."

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