In the 802.11 frame, what is the interframe interval between RTS and CTS?

Question

Options

• ASIFS
• BIFS
• CDIFS
• DPIFS

• A
  84% (48)
• B
  2% (1)
• C
  9% (5)
• D
  5% (3)

Explanation

SIFS (Short Interframe Space) is used between RTS and CTS because it is the shortest interframe gap, reserved for high-priority, immediate-response exchanges that must complete without interruption - including RTS/CTS, CTS/DATA, and DATA/ACK sequences. DIFS (Distributed Coordination Function IFS) is incorrect because it is a longer gap used by stations waiting to begin a new transmission under the DCF access method, not for responding within an ongoing exchange. PIFS (PCF IFS) is incorrect because it is used by the Point Coordinator under PCF mode to gain priority access to the medium, and sits between SIFS and DIFS in length. IFS is simply the generic term for "interframe space" and does not name a specific interval defined in the 802.11 standard, making it incorrect as a precise answer.

Memory tip: Think of SIFS as the "reply gap" - any frame that is a direct response to another frame (CTS replying to RTS, ACK replying to DATA) uses SIFS because the exchange must finish before other stations can cut in.

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