In the 802.11 frame, when the wireless workstation sends a signal to the wireless AP, what are the values of To DS and From DS?

Question

Options

• A0, 0
• B0, 1
• C1, 0
• D1,1

• A
  14% (6)
• B
  5% (2)
• C
  75% (33)
• D
  7% (3)

Explanation

Option C (To DS=1, From DS=0) is correct because when a wireless workstation sends a frame to an Access Point, the frame is traveling toward the Distribution System (the wired network infrastructure behind the AP), so To DS is set to 1, while From DS is 0 because the frame did not originate from the DS. Option A (0,0) applies to ad-hoc (IBSS) frames where no AP is involved at all. Option B (0,1) is the reverse scenario: a frame traveling from the AP down to the workstation, meaning it came FROM the DS. Option D (1,1) is used in Wireless Distribution System (WDS) configurations where two APs communicate with each other, bridging traffic between them.

Memory tip: Think of the direction of travel relative to the wired network. A workstation sending to an AP is sending data INTO the network, so To DS=1 and From DS=0. Flip both bits for the return trip (AP to workstation). Ad-hoc has no DS at all (both 0), and AP-to-AP bridging uses both (both 1).

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