CWAP PW0-270 問題集

質問 1：
As it pertains to HT L-SIG TXOP Protection, what statement is true?
A. Support for L-SIG TXOP Protection is indicated by HT stations in the L-SIG field of the PLCP header of HT-mixed format frames.
B. Support for L-SIG TXOP Protection is indicated in the HT Capabilities Info field of (re)association request frames sent by ERP, OFDM, and HT-OFDM stations.
C. An L-SIG TXOP protected frame exchange sequence always begins with an RTS/CTS or a CTS-to-Self.
D. L-SIG TXOP Protection is specified for the purpose of protecting OFDM (802.11a/g) and HTOFDM (802.11n) transmissions from HR/DSSS stations.
正解：C

質問 2：
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 3：
According to the IEEE 802.11 standard, what is one structural difference between a MAC Protocol Data Unit (MPDU) and a MAC Management Protocol Data Unit (MMPDU)?
A. The MPDU frame's FCS field is 4 bytes, while the MMPDU frame's FCS field is 8 bytes.
B. The MMPDU frame body is limited to 300 bytes, whereas the MPDU frame body can carry up to 2304 bytes.
C. Both the MPDU and MMPDU have a QoS Control (QC) field, but all bits of the MMPDU's QC field are always 0.
D. An MMPDU header may only contain three address fields, but an MPDU may have four address fields.
E. The MPDU header always places the BSSID in the first address field, but in the MMPDU the BSSID can be found in any of the address fields.
正解：D

質問 4：
As a WLAN consultant, you have been asked to troubleshoot a problem with a single wireless client station (Station-Z). Your customer informs you that other wireless client stations are not having problems with wireless connectivity, and that Station-Z is configured in the same manner as all other wireless client stations on the network. Station-Z is showing an unusually high retransmission count in its client utility statistics. Using a wireless protocol analyzer, where and how should you begin troubleshooting this problem? (Choose 2)
A. Position the analyzer near Station-Z. Analyze Station-Z's transmissions and acknowledgements. Look for RF and obstacle-induced interference.
B. Position the analyzer near the access point. See if Station-Z's frames are reaching the access point and if so, analyze their signal strength.
C. Position the analyzer halfway between Station-Z and the access point. Analyze the data rate at which frames are sent and how long they take to be received.
D. Position the analyzer near Station-Z. Analyze the frames Station-Z is receiving, looking for delayed ACK frames.
E. Position the analyzer halfway between Station-Z and the access point. Measure the distance between Station-Z and the access point.
正解：A,B

質問 5：
When a client station operating under EDCA sends an RTS frame and NAV protection is desired for only the first or sole frame in the TXOP, the duration field will contain an amount of time, measured in microseconds, equal to which of the following?
A. 1 RTS, 2 ACK, 1 DATA, 4 SIFS
B. 1 CTS, 1 ACK, 1 DATA, 3 SIFS
C. 1 RTS, 1 CTS, 2 ACK , 1 DATA, 4 SIFS
D. The entire duration of the TXOP
E. 1 RTS, 1 ACK, 1 DATA, 2 SIFS, 1 DIFS
F. 1 CTS, 2 ACK, 1 DATA, 2 SIFS
正解：B