Q2.Marks: +2.0UGC NET Paper 2: Computer Science 2nd January 2026 Shift 1
Arrange the following interframe time interval in increasing order.
A. PIFS(PCF interframe Spacing)
B. DIFS(DCF interframe Spacing)
C. SIFS(Short interframe Spacing)
D. EIFS (Extended interframe Spacing)
Choose the correct answer from the options given below:
1.A, B, C, D
2.B, C, A, D
3.D, A, B, C
4.C, A, B, D✓ Correct
Solution
The correct answer is C, A, B, D.
Key Points
SIFS (Short Interframe Spacing): It is the shortest interframe time interval used for high-priority transmissions like acknowledgments and RTS/CTS frames.
PIFS (PCF Interframe Spacing): This is slightly longer than SIFS and is used by the Point Coordination Function to gain access to the medium before DCF.
DIFS (DCF Interframe Spacing): It is longer than both SIFS and PIFS and is used for contention-based access under the Distributed Coordination Function.
EIFS (Extended Interframe Spacing): This is the longest interframe time interval, used for retransmissions in response to corrupted frames.
Additional Information
IEEE 802.11 Standards:
Interframe time intervals are crucial in determining the priority of access to the wireless medium.
SIFS is used for time-critical operations like acknowledgments and control frames.
PIFS enables PCF to access the medium before DCF-based devices.
DIFS is used for regular data transmissions under contention-based access.
EIFS is used as a recovery mechanism after detecting frame corruption.
Purpose of Interframe Spacings:
Ensures efficient and fair access to the wireless medium.
Allows prioritization of critical transmissions over regular data frames.
Helps in avoiding collisions and maintaining network stability.
Important Points:
Interframe spacings are predefined durations based on the IEEE 802.11 protocol.
The correct arrangement of these intervals helps in understanding the hierarchical access mechanism in wireless networks.
