CWAP PW0-270 問題集

質問 1：
Which statement is true regarding the Association Identifier (AID) used in IEEE 802.11 WLANs?
A. The AID has a maximum value of 2007, and resides in the duration/ID field of a PS-Poll frame.
B. The AID field is present only in Beacons frames.
C. The client station is assigned an AID value in the 802.11 authentication response frame.
D. The AID has a maximum value of 2048, and is used to uniquely identify a wireless client station associated with an access point.
E. The AID is used by the access point in EDCA mode to reduce duplicate transmissions when sending multicasts.
正解：A

質問 2：
IEEE 802.11-2007 specifies two ERP protection mechanisms: RTS/CTS and CTS-to-Self. Which statement is true regarding these two protection mechanisms? (Choose 2)
A. Aside from the Subtype subfield of the Frame Control field, the generic MAC header format of RTS and CTS frames are identical.
B. Use of RTS/CTS requires more overhead than CTS-to-Self due to a higher number of frames transmitted onto the wireless medium.
C. By definition, all associated client stations in a BSS can hear RTS, CTS, and CTS-to-Self frames, so RTS/CTS and CTS-to-Self mechanisms have equal effectiveness.
D. A CTS-to-Self frame sent by a client station may reach fewer nodes than the RTS/CTS frame exchange.
E. RTS and CTS frames are relayed through the access point, whereas the CTS-to-Self frames are not.
F. RTS and CTS frames use Short Interframe Spaces (SIFS), and CTS-to-Self frames use PCF Interframe Spaces (PIFS).
正解：B,D

質問 3：
The IEEE 802.11 Dynamic Frequency Selection (DFS) service is capable of performing what functions? (Choose 2)
A. Testing channels for radar before using a channel and while operating in a channel
B. Establishing an interference baseline on all 2.4 GHz channels
C. Using modulation switching techniques to avoid interfering with radar systems
D. Requesting and reporting of measurements in the current and other channels
E. Suspending operations on a channel with high IEEE 802.11 co-channel interference
正解：A,D

質問 4：
Given: The graphic is taken from a spectrum analyzer.

What types of RF transmitters are illustrated?
A. An IEEE 802.11 HR/DSSS security camera on channel 6 and an RFID tag
B. A Bluetooth headset and a narrowband RF jamming device
C. A 2.4 GHz cordless phone and an OpenAir FHSS system
D. A 20 MHz HT IEEE 802.11 system using channel 1 and a microwave oven
正解：D

質問 5：
What HT PPDU format is shown in the exhibit?

A. ERP-OFDM format
B. HT-mixed format
C. HT-greenfield format
D. Non-HT format
E. Dual Training Field format
F. Non-HT duplicate format
正解：B

質問 6：
In which 802.11 frames is the SSID present, provided the SSID is not removed through proprietary software configuration by an administrator? (Choose 3)
A. Probe Response
B. Association Response
C. Authentication
D. Reassociation Request
E. Disassociation
F. Association Request
正解：A,D,F