Braindumps for "PW0-205" Exam

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Question 1.

In an 802.11b PLCP header, what does the 16-bit length field indicate?



A. The size in octets of the MPDU being transferred in the PPDU

B. The length of time in kilo microseconds it will take to transmit the PSDU

C. The length of time in microseconds it will take to transmit the MPDU

D. The size in bits of the entire PPDU frame



Answer: C



Question 2.

Which of the following must be true before an 802.11 station may transmit a 
frame on the RF medium using DCF mode?



A. The Network Allocation Vector must be equal to zero.

B. A time period of at least PIFS must have passed.

C. The station must have received a PS-Poll frame from the access point.

D. The Back off Timer must be equal to zero.

E. A time period of at least DIFS must have passed.

F. All collision arbitration must be completed on the RF medium.



Answer: A, D, E



Question 3.

What is an advantage of being able to fragment MSDUs and MMPDUs on a wireless 
network?



A. Increased throughput in a clean RF environment

B. Increased throughput due to interference from other 802.11 stations.

C. Increased throughput in an 802.11b/g mixed mode environment.

D. Decreased retransmission overhead in a noisy RF environment.

E. Decreased translation time between 802.3 and 802.11 networks at the access 
point.

F. Decreased number of 802.11 control and management frames required for 
transmission.



Answer: D



Question 4.

How long, in microseconds, is the Slot Time mandated for use in the BSS by an 
802.11g access point when both 802.11b and 802.11g client stations are 
associated to it?



A. 2 us

B. 5 us

C. 9 us

D. 10 us

E. 20 us



Answer: E



Question 5.

As a wireless LAN consultant, you have been contacted by one of your customers 
to go to their premises 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 utilities. 



Using a wireless protocol analyzer, where and how would you begin 
troubleshooting this problem?



A. Position the analyzer half way between Station-Z and the access point. 
Analyze the distance 

between Station-Z and the access point.

B. Position the analyzer near Station-Z. Analyze Station-Z transmissions and 
acknowledgements. 

Look for RF and obstacle-induced interference.

C. Position the analyzer near the access point. See if Station-Z frames are 
reaching the access 

point and if so, analyze their signal strength.

D. Position the analyzer near Station-Z. Analyze the frames Station-Z is 
receiving, looking for 

corrupted frames.

E. Position the analyzer half way between Station-Z and the access point. 
Analyze the data rate 

at which frames are sent and how long they take to be received.



Answer: B, C



Question 6.

When an 802.11i-compliant wireless LAN security solution is being used with 
IPSec/ESP, what will a wireless LAN protocol analyzer see as the security 
mechanism in use?



A. TKIP or CCMP

B. IPSec/ESP

C. Unknown protocol

D. Both WEP and IPSec/ESP



Answer: A



Question 7.

An 802.11b client station sends a single 600 byte MSDU to another 802.11b client 
station while operating as part of an unsecured infrastructure BSS. Due to 
thresholds set on all client stations and the access point, all MPDUs over 300 
bytes in length invoke the RTS/CTS protocol. 



How many individual CTS frames are transmitted on the wireless medium as part of 
the entire process of moving the 600 byte MSDU between the two client stations?



A. 1

B. 2

C. 3

D. 4



Answer: B



Question 8.

Errors at the PLCP layer are common in wireless LANs. 



Which of the following is NOT a common PLCP error type?



A. PLCP CRC Errors

B. PLCP Format Errors

C. PLCP Length Errors

D. PLCP Overrun Errors



Answer: D



Question 9.

On an 802.11 wireless LAN operating in DCF, when the last frame received 
contains errors, which of the following timing intervals are used?



A. Super frame

B. Extended Inter frame Space

C. Slot Time

D. Contention-free Repetition Interval

E. DCF Inter frame Space



Answer: B



Question 10.

There are many differences between analyzing wireless and wired networks. In a 
wireless network, there is no guarantee one wireless client station can hear 
another station's transmissions. 



With no corrective actions or corrective mechanisms implemented, this hidden 
node situation may cause which measurable statistics parameter to be incremented 
in a wireless protocol analyzer?



A. Duration length

B. Retransmission Count

C. Contention Window

D. Slot Time

E. Fragment Interval

F. DTIM Interval



Answer: B



Question 11.

There are many wireless LAN scanners on the market such as Net Stumbler, Kismet, 
Mac Stumbler, and others that can aid in finding the SSID of wireless LANs. In 
order to defeat the efforts of these scanners, some administrators configure 
their access points to stop broadcasting SSIDs in Beacons and not to respond to 
Probes with null (empty) SSID fields. 



Describe how wireless LAN protocol analyzers can circumvent this so-called 
"security" solution.



A. Wireless LAN protocol analyzer software puts the radio card driver into RF 
Monitor mode. This 

mode is recognized by access points as privileged, allowing them connectivity 
when it would 

otherwise be denied.

B. Wireless LAN protocol analyzers send specialized Probe Requests to which 
802.11 compliant 

access points are required to respond with a Probe Response containing the SSID


information.

C. Wireless LAN protocol analyzers use a special driver, used to operate the 
card in promiscuous 

mode. Promiscuous mode is a special mode allowing the radio card to see raw data 
frames, 

instead of the filtered data frames that standard mode radio cards see.

D. Wireless LAN protocol analyzers analyze all frames on a wireless LAN. Frame 
types other 

than Beacons and Probe Responses carry the SSID information.

E. Wireless LAN protocol analyzers using cards from the same manufacturer as the 
access point 

will always be able receive the SSID due to the proprietary chipset protocol 
extensions.



Answer: D



Question 12.

Access points act as translational bridges (portals), bridging traffic between 
802.11 and 802.3 networks. 



What two specifications are used most often by access points to perform this 
frame translation?



A. 802.1H

B. 802.11d

C. RFC 2002

D. RFC 1042

E. 802.3z



Answer: A, D



Question 13.

When an access point sends an RTS frame, the duration field will contain an 
amount of time, measured in microseconds, equal to which of the following?



A. 2 ACK, 1 RTS, 1 DATA, 4 SIFS

B. 1 ACK, 1 CTS, 1 DATA, 3 SIFS

C. 1 DATA, 1 RTS, 2 SIFS, 1 DIFS, 1 ACK

D. 1 RTS, 1 CTS, 1 DATA, 2 ACK, 4 SIFS



Answer: B



Question 14.

Bill works at Company.com help desk. Around lunch time, Bill gets a call asking 
for the password of network user Shazaam. Bill gives the caller some erroneous 
information about user Shazaam, and immediately contacts Company.com security 
department about a social engineering attack. 



Bill is trained to recognize Shazaam as a red alert, but how does Bill know that 
a social engineering attack is in progress?



A. Company.com uses 802.1x/PEAP-EAP-TLS as their wireless security protocol for 
user 

authentication, and PEAP has a programmable integrated intrusion detection 
mechanism 

currently named Shazaam. This intrusion mechanism is picked up, in clear text, 
on wireless 

protocol analyzers as a user name.

B. Company.com uses FakeAP as a protection mechanism against hackers. FakeAP is 
a utility 

that transmits thousands of fake management frames that can confuse hackers. 
Shazaam has 

been configured as a fake user name in these management frames and can be seen 
on a 

wireless protocol analyzer.

C. Company.com uses 802.1X/EAP-TTLS as their wireless security protocol for user


authentication, and EAP-TTLS uses an "anonymous" user name outside the TLS 
tunnel. In 

this case, the anonymous user is named Shazaam, and it can be seen in clear text 
on a 

wireless protocol analyzer.

D. Company.com uses IPSec VPNs to secure their wireless LAN. IPSec VPNs use an


"anonymous" name field during the authentication process when using digital 
certificates. The 

network administrator has configured all wireless client stations to use Shazaam 
in the 

anonymous name field so that wireless protocol analyzers will mistakenly think 
it is a real user 

name.



Answer: C



Question 15.

In order to increase throughput in an IEEE 802.11b/g mixed mode environment 
where 802.11b and 802.11g stations are both actively participating in a BSS, the 
DSSS-OFDM modulation was introduced in the 802.11g supplement. 



How does DSSS-OFDM increase throughput in a mixed mode environment?



A. An OFDM preamble and header are used along with a DSSS payload.

B. An OFDM preamble is used along with a DSSS header and payload.

C. An OFDM preamble and payload are used along with a DSSS header and FCS.

D. A DSSS preamble is used along with an OFDM header, payload, and FCS.

E. A DSSS preamble and payload are used, along with an OFDM header.

F. A DSSS preamble and header are used along with an OFDM payload.



Answer: F



Question 16.

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 FCS field is 4 bytes, while the MMPDU frame FCS field is 8 
bytes.

B. The MMPDU frame body is limited to 200 bytes, whereas the MPDU frame body can 
carry up 

to 2312 bytes.

C. 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.

D. An MMPDU header may only contain three address fields, but an MPDU may have 
four 

address fields.



Answer: D



Question 17.

Which of the following information will a wireless LAN protocol analyzer capture 
if it can only capture Data Link information?



A. Source IP Address

B. Null Function Data frames

C. TCP SYN datagram

D. Short Inter frame Spaces

E. Sequence Control fields



Answer: B, E



Question 18.

An 802.11b PPDU's preamble consists of two fields and can collectively be 
considered "long" or "short" by the 802.11b standard. Which of the following is 
true regarding the PLCP preamble?



A. A long preamble uses a Sync field of 128 bits, and both stations and access 
points may have 

configurable preamble lengths.

B. A short preamble uses a Sync field of 40 bits, and stations and access points 
must have 

matching preamble lengths in order to communicate.

C. Long and short preamble lengths are both variable depending on the modulation 
in use on the 

network, and access points always inform stations of the preamble length in use 
on the 

network.

D. When short preambles are being used, the Sync and SFD fields both consist of 
16 bits. Only 

access points have configurable preamble lengths.

E. An 802.11b access point that supports both long and short preambles may allow 
stations that 

are using different preamble lengths to communicate through it simultaneously.

F. 802.11g stations associating to 802.11b access points must use the DSSS 
preamble length 

specified by the access point.



Answer: A, F



Question 19.

An Announcement Traffic Indication Message (ATIM) frame is used by stations 
operating in an IBSS to notify other stations of their intention to transmit 
data. 



Which fixed fields and information elements does the ATIM frame include?



A. SSID and Supported Rates

B. Capability Information and Timestamp

C. Challenge Text and Authentication Algorithm

D. IBSS Parameter Set and Status Code

E. The ATIM contains no fixed fields or information elements



Answer: E



Question 20.

Given the 802.11 frame decode shown, which of the following statements are true.




A. This screenshot was taken from a Probe Response frame.

B. No mobile stations in this BSS have traffic queued at the access point

C. The TIM is also a DTIM

D. The Beacon Interval is 100 milliseconds

E. This screenshot was captured in an Ad Hoc (IBSS) network



Answer: B, C



Question 21.

James is a sales associate for Company.com. Sitting at his desk, James can use 
the wireless LAN with no problems. James takes his laptop downstairs to 
Company.com Engineering department. James finds that he cannot connect to the 
Internet or the company intranet, but his wireless LAN card utilities shows that 
he is associated to the wireless network. Engineers are reporting no network 
connectivity problems over the wireless LAN. 



When using a protocol analyzer, what will you most likely find as the cause of 
the problem?



A. Company.com administrator has configured different security mechanisms for 
the Sales and 

Engineering departments.

B. James has a static IP configured on his laptop, and he has now roamed across 
a layer 3 

network boundaries.

C. An ARP storm is consuming the wireless medium bandwidth making network 
connectivity 

almost impossible.

D. Company.com administrator has configured protocol filters on the Engineering 
department 

access points.

E. Someone has placed a rogue DHCP server on the Engineering network.



Answer: B



Question 22.

During Contention-Free operation, a poll able client station is allowed to send 
which of the following frame types to the Point Coordinator?



A. Null Function

B. Data + CF-Poll

C. Data + CF-Ack

D. CF-Ack + CF-Poll

E. Data + CF-Poll + CF-Ack



Answer: A, C



Question 23.

Some protocol analyzers have the ability to capture only MAC frame headers 
(sometimes called packet slicing), and others have the ability to update the 
capture display without saving the frames permanently (sometimes called 
stumbling mode). 



What are advantages of using these two features of a wireless protocol analyzer?



A. Analyzers with a small amount of frame buffer memory can be used.

B. Analyzers can use DRAM to store captured frames instead of storing files on a 
hard drive.

C. Capturing, analyzing, and discarding headers allows more CPU cycles for 
real-time decoding 

and analysis.

D. Analyzers can be left running for long periods of time without running out of 
frame buffer 

space.

E. Analyzers can capture traffic on more channels simultaneously due to 
decreased overhead per 

channel.



Answer: A, D



Question 24.

A wireless network administrator has examined the frame retry counts on several 
client stations in a WLAN that is not using encryption, and has determined that 
they are extraordinarily high. For this reason, he has decided to configure 
station fragmentation thresholds to 400 bytes. 



With this configuration change, when a data frame with a 1500 byte MSDU is 
transmitted by one of the wireless client stations to a wired station through an 
access point, what will be the order and size (in bytes) of the fragments as 
they're transmitted?



A. Frame1 = 400, Frame2 = 400, Frame3 = 400, Frame4 = 300

B. Frame1 = 300, Frame2 = 300, Frame3 = 300, Frame4 = 300, Frame5 = 300

C. Frame1 = 300, Frame2 = 400, Frame3 = 400, Frame4 = 400

D. Frame1 = 400, Frame2 = 400, Frame3 = 400, Frame4 = 400, Frame5 = 40

E. The fragmentation threshold setting on client stations only affects received 
frames, not 

transmitted frames

F. The fragmentation threshold setting on client stations is not a manual 
adjustment, and can only 

be auto-configured by access points



Answer: D



Question 25.

When an 802.11 station operating in Power Save mode with a Receive DTIMs 
parameter of TRUE receives a beacon containing a DTIM indicating queued 
broadcast traffic, what task does the 802.11 standard require the client station 
to perform?



A. The client station must send a PS-Poll frame to the access point for every 
broadcast frame it 

receives with the More Data bit set to one.

B. The client station must send an ATIM frame to the access point if the station 
is the first AID in 

the DTIM list.

C. The client station must arbitrate for the medium and immediately issue an RTS 
directed to the 

access point with the NAV set to a value of 32,768.

D. The client station must broadcast a CTS-to-Self frame indicating the station 
need to control the 

medium long enough to receive all of the broadcast frames.

E. The client station must send a CF-Poll Response frame to the access point 
with the Reason 

Code set to 0x00.

F. To remain awake to receive the broadcast frame(s) to follow the beacon that 
contains the 

DTIM.



Answer: F



Question 26.

What, if any, compatibility problems might arise if an 802.11b client station 
wireless network interface card (NIC) configured for use in Europe is used with 
an 802.11b access point configured for use in the United States?



A. No compatibility problems would occur because the physical layer of the 
802.11b standard is 

the same world-wide.

B. The station NIC might not be able to talk to the access point because Europe 
and the U.S. use 

different channel sets.

C. No compatibility problems would arise because the wireless NIC is capable of 
operating on 

any channel specified by the 802.11b access point.

D. The NIC would not see the access point at all because European 802.11b radios 
use Hyper 

Channel encoding at the physical layer.



Answer: C



Question 27.

In the graphic, there are three active 802.11b access points. These access 
points are on channels 1, 6, and 11. In the graph to the left, signals on 
channels 1, 6, and 11 are shown in green bars above their channel number. 



What do the brown bars on channels 2, 3, 5, 7, 10, and 12 represent?



A. Transmission echoes (multi path)

B. Channel harmonics (resonant frequencies)

C. Cross channel interference

D. Stations associated to the channel 1, 6, & 11 access points

E. Transmissions on adjacent channels by DSSS access points that are not part of 
this wireless 

LAN system

F. Unassociated stations sending probe request frames trying to locate an access 
point with 

which to associate



Answer: C



Question 28.

While analyzing a small office wireless network, you notice WEP is in use. In 
your protocol analyzer, where would you look to view the WEP Initialization 
Vector (IV) information?



A. In any Data frame Frame Control field.

B. It is not possible to view the IV information because it is encrypted.

C. In any Data frame Sequence Control field.

D. In any MPDU frame body.

E. In any PPDU header Service field.



Answer: D



Question 29.

Which two of the following sets of 802.11 control frames have the same frame 
format and address positions?



A. RTS and ACK

B. CTS and ACK

C. RTS and CTS

D. CF-End+CF-ACK and CF-End

E. RTS and CF-Poll

F. PS-Poll and CF-End



Answer: B, D



Question 30.

What is indicated when the ToDS and From DS bits are set to 1 in the Frame 
Control field?



A. The frame is being transmitted from a wired station to a wireless client 
station.

B. The frame is being transmitted from one wireless client station to another 
wireless station 

within the same BSS

C. The frame is being transmitted from a wireless client station to a wired 
station.

D. The frame is being transmitted between two access points over a wireless 
distribution system.

E. The frame is being transmitted from a wireless client station to an access 
point where the 

frame terminates at the access point.



Answer: D



Question 31.

When capturing traffic using a wireless LAN protocol analyzer that has a single 
2.4 GHz radio card, which of the following is true?



A. All traffic on one 2.4 GHz channel and its directly adjacent channels can be 
captured 

simultaneously.

B. All traffic on all 2.4 GHz channels can be captured simultaneously.

C. All traffic on only one 2.4 GHz channel can be captured at any given time.

D. The number of channels that an analyzer can capture simultaneously is 
dependent on the 

vendor implementation.



Answer: C



Question 32.

The Timestamp field, found in 802.11 Beacon Management frames, is 8 bytes in 
length and serves which of the following purposes?



A. Keeps all client stations in a BSS synchronized to within approximately 4 
microseconds of the 

access point.

B. Allows client stations in the IBSS to pick the best of multiple beacons.

C. Used to notify client stations using power management features of how long 
their queued 

frames have been held by the access point.

D. Informs associating client stations how often to expect Beacon Management 
frames to be sent 

by the access point.

E. Allows all client stations in a BSS to calculate how long it took for the 
Beacon Management 

frame to traverse the wireless medium.



Answer: A, B



Question 33.

In which of the following IEEE 802.11a frames can the SSID be found providing 
the SSID is not specifically removed through firmware configuration by an 
administrator?



A. Association Request

B. Re-association Request

C. Probe Response

D. Disassociation

E. Authentication

F. Re-association Response



Answer: A, B, C



Question 34.

Company.com's wireless LAN administrator is getting complaints from one user 
that his wireless LAN throughput is sluggish compared to other users in his 
area. The administrator takes his diagnostics laptop, which has a wireless 
protocol analyzer installed, to the area where the complaining user works. 



The administrator uses the PING utility to test connectivity from the 
complaining user's wireless client station to another wireless client station 
across the closest access point, while capturing the wireless frames. 



The administrator sees what is displayed in this screenshot. From this 
screenshot, which of the following statements can you conclude to be true that 
are related to the complaining user's throughput problem?



Exhibit:



A. The complaining user's wireless LAN client utilities are configured for a 
small fragmentation 

threshold.

B. The complaining user's station is retransmitting fragments many times likely 
due to nearby RF 

interference

C. The access point is 802.11g, and the complaining user's wireless client 
station is 802.11b

D. The complaining user's wireless client station should be using RTS/CTS as a 
protection 

mechanism, but it is not.

E. The access point is not signaling for protection (Protection = no) in the 
Beacons, but it should 

be.



Answer: A, C



Question 35.

Which of the following IEEE 802.11 units has a 16-bit frame check sequence 
(FCS)? 



A. 802.11 MAC Protocol Data Unit (MPDU)

B. 802.11a MPDU Frame Control field

C. 802.11b Physical Layer Convergence Protocol (PLCP) header

D. 802.11 Wired Equivalent Privacy (WEP)

E. 802.11g Announcement Traffic Indication Message (ATIM)



Answer: C



Question 36.

An administrator for Company.com has noticed an intermittently high number of 
retransmissions on their purely 802.11g wireless LAN coming from some of the 
access points near the break room, especially when wireless stations are using 
the FTP protocol to pull down large sales report data files from the company's 
FTP server. The administrator decides to hire a consultant to test some 
configuration changes hoping to improve performance of the wireless LAN. As the 
consultant, what test do you recommend performing?



A. Decrease the output power on all access points and stations throughout the 
ESS to form 

smaller cells in case there is a hidden node.

B. Enable support of short preambles on all access points near the break room.

C. Change the DTIM interval in all access points near the break room to a 
shorter interval.

D. Change the fragmentation threshold value on all access points near the break 
room to a 

smaller value.

E. Set all supported data rates on the access points near the break room to 
Basic



Answer: D



Question 37.

Company.com has two access points (AP-1 and AP-2) connected to an Ethernet hub.




Which of the following describes how the access points will handle a frame sent 
from a wired node to a wireless station associated to AP-1?



A. AP-1 will check its association table and broadcast the frame onto the 
wireless medium. AP-2 

will check its association table and drop the frame.

B. AP-1 will check its association table and broadcast the frame onto the 
wireless medium. AP-2 

will check its switching table and forward the frame to AP-1.

C. AP-1 will automatically forward the frame onto the wireless medium. AP-2 will 
notify the wired 

node that it does not have an association ID for the station.

D. AP-1 and AP-2 will automatically forward the frame onto the wireless medium 
regardless of 

any other criteria.

E. AP-1 and AP-2 will both issue ARP frames onto the wireless medium, and if 
they receive a 

reply, they will broadcast the data frame onto the wireless medium.



Answer: A



Question 38.

In an 802.11 wireless LAN frame with either long or short preambles, the PLCP 
Header consists of multiple fields. 



Which of the following are valid PLCP Header fields?



A. Sync

B. Signal

C. FCS

D. MSDU

E. SFD



Answer: B, C



Question 39.

Which of the following physical layer parameters are implemented differently in 
OFDM systems and HR/DSSS systems?



A. Slot Time values

B. RTS/CTS implementation

C. PLCP Preamble format

D. DCF medium access

E. MPDU FCS algorithm

F. Available PPDU payload value



Answer: A, C



Question 40.

When the To DS bit is set to 1 and the From DS bit is set to 0 in the Frame 
Control field of an 802.11 Data frame, what might this indicate about the 
infrastructure and the wireless conversation?



A. A wireless client station could be sending data to a wired station through an 
access point.

B. A wireless client station must be sending data to a wireless station where 
the frame has to 

traverse a Wireless Distribution System (WDS).

C. A wireless client station must be sending data directly to the access point 
for the purpose of 

managing the access point.

D. A wireless client station could be sending data to a wireless client station 
across an access 

point.

E. A wireless client station could be sending data directly to another wireless 
client station as part 

of an IBSS.



Answer: A, D



Question 41.

Company.com is using a single 802.11g access point in their New York branch 
office. There are ten 802.11g wireless client stations currently on the network, 
each used by XYZ full-time employees. XYZ has hired a consultant to work on some 
accounting problems, and he is using an 802.11b radio card in his laptop. 



How might this affect XYZ wireless LAN throughput?



A. There will be no affect on the wireless LAN throughput capacity since the 
access point talks to 

each station at the highest rate at which the station is capable of 
transmitting.

B. The network throughput capacity will remain unchanged, but the 802.11b client 
station will 

slow access down for the 802.11g stations.

C. The network throughput capacity will be greatly decreased, and each 802.11g 
client station 

must begin using 20 us slot times.

D. The network throughput capacity will decrease slightly since the only change 
will be that the 

802.11b client station will transmit at 11 Mbps instead of 54 Mbps.

E. The network throughput capacity will greatly decreased due to mandatory use 
of DSSS-OFDM 

modulation.



Answer: C



Question 42.

Before accurate statistical troubleshooting with a wireless protocol analyzer 
can be performed on a wireless LAN, which of the following must be completed?



A. Traffic injection analysis

B. Operational traffic policy

C. Directional traffic filtering

D. Baseline traffic analysis

E. Quality of Service (QoS) design



Answer: D

 

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