13, 15, 10

Question 1

How long do all Wi-Fi radios have to exit a dynamic frequency selection (DFS) channel when a radar pulse is detected?

A. 10 seconds
B. 30 seconds
C. 60 seconds
D. 30 minutes
E. 60 minutes

Answer 1

A. 10 seconds

Question 2

What WLAN client connectivity may be negatively impacted by client load balancing between access points?

A. Capacity
B. Range
C. Roaming
D. Throughput
E. Security

Answer 2

C. Roaming

Question 3

What are some potential problems when enabling 40 MHz channels in the 5 GHz band? (Choose all that apply.)

A. Adjacent channel interference
B. Co-channel interference
C. Higher SNR
D. Lower SNR
E. Decreased range

Answer 3

B. Co-channel interference
D. Lower SNR

Question 4

What are some recommendations when using 40 MHz channels in the 5 GHz band? (Choose all that apply.)

A. Enable the DFS channels.
B. Lower AP transmit power.
C. Verify wall attenuation.
D. All of the above

Answer 4

D. All of the above

Question 5

How many client devices can successfully connect to and communicate with an AP?

A. 35
B. 50
C. 100
D. 250
E. It depends.

Answer 5

E. It depends.

Question 6

What are some questions that should be considered during WLAN client capacity planning?

A. How many users and devices need access currently?
B. How many users and devices will need access in the future?
C. Where are the users and devices located?
D. What are the MIMO capabilities of the client devices?
E. What type of applications will be used for the WLAN?
F. All of the above

Answer 6

F. All of the above

Question 7

Which is the preferred channel and power configuration method for enterprise Wi-Fi APs? (Choose all that apply.) 2

A. Adaptive RF in standard RF environments
B. Static channel and power settings in standard RF environments
C. Adaptive RF in complex RF environments using directional antennas
D. Static channel and power settings in complex RF environments using directional antennas

Answer 7

A. Adaptive RF in standard RF environments
D. Static channel and power settings in complex RF environments using directional antennas

Question 8

What is the biggest problem when enabling 5 GHz dynamic frequency selection (DFS) channels?

A. Channel switch announcements
B. False positives
C. Co-channel interference
D. Adjacent channel interference
E. The 60-second wait time

Answer 8

B. False positives

Question 9

To reduce airtime consumption and provide for better capacity in the 5 GHz band, which data rates are recommended to be selected as basic rates? (Choose all that apply.)

A. 6 Mbps
B. 9 Mbps
C. 12 Mbps
D. 18 Mbps
E. 24 Mbps

Answer 9

C. 12 Mbps
E. 24 Mbps

Question 10

How long must an AP listen on a DFS channel before transmitting?

A. 10 seconds
B. 30 seconds
C. 60 seconds
D. 30 minutes
E. 60 minutes

Answer 10

C. 60 seconds

Question 11

What is the main cause of co-channel interference?

A. Microwave interference on the same channel within hearing range
B. APs on the same channel within hearing range
C. APs on a different channel within hearing range
D. Clients on the same channel within hearing range
E. Clients on a different channel within hearing range

Answer 11

D. Clients on the same channel within hearing range

Question 12

What percentage of cell overlap is needed to provide for seamless roaming?

A. 10 percent
B. 15 percent
C. 20 percent
D. 25 percent
E. This is a trick question.

Answer 12

E. This is a trick question.

Question 13

How many channels should be used in a 5 GHz channel reuse pattern of 20 MHz channels?

A. 3
B. 4
C. 8
D. 12
E. As many as available

Answer 13

E. As many as available

Question 14

What is the recommended received signal and SNR when providing for VoWiFi client communications?

A. –70 dBm and 20 dB
B. –70 dBm and 25 dB
C. –70 dBm and 15 dB
D. –65 dBm and 15 dB
E. –65 dBm and 25 dB

Answer 14

E. –65 dBm and 25 dB

Question 15

What type of interference is a result of APs on the same channel or clients on the same channel hearing each other despite being members of different basic service sets?

A. Intersymbol interference
B. Adjacent channel interference
C. All-band interference
D. Co-channel interference
E. Narrowband interference

Answer 15

D. Co-channel interference

Question 16

What type of interference is caused by overlapping coverage cells with overlapping frequencies?

A. Intersymbol interference
B. Adjacent channel interference
C. All-band interference
D. Co-channel interference
E. Narrowband interference

Answer 16

B. Adjacent channel interference

Question 17

How many channels should be used in a channel reuse plan for the 2.4 GHz frequency band?

A. 3
B. 4
C. 6
D. 11
E. 13

Answer 17

A. 3

Question 18

Based on RSSI metrics, concentric zones of variable data rate coverage exist around an access point due to the upshifting and downshifting of client stations between data rates. What is the correct name of this process, according to the IEEE 802.11-2020 standard?

A. Dynamic rate shifting
B. Dynamic rate switching
C. Automatic rate selection
D. Adaptive rate selection
E. All of the above

Answer 18

B. Dynamic rate switching

Question 19

Given: Wi-Fi clients can roam seamlessly at layer 2 if all the APs are configured with the same SSID and same security settings. However, if clients cross layer 3 boundaries, a layer 3 roaming solution will be needed. Which device functions as the home agent if a Mobile IP solution has been implemented in an enterprise WLAN environment where no WLAN controller is deployed?

A. Wireless network management server (WNMS)
B. Access layer switch
C. Layer 3 switch
D. Access point on the original subnet
E. Access point on the new subnet

Answer 19

D. Access point on the original subnet

Question 20

What is a telecommunications unit of measurement of traffic equal to one hour of telephone traffic in one hour of time?

A. Ohm
B. dBm
C. Erlang
D. Call hour
E. Voltage standing wave ratio

Answer 20

C. Erlang

Question 21

At which layer of the OSI model do most networking problems occur?

A. Physical
B. Data-Link
C. Network
D. Transport
E. Session
F. Presentation
G. Application

Answer 21

A. Physical

-Regardless of the networking technology, the majority of problems occur at the Physical layer of the OSI model. The majority of performance and connectivity problems in 802.11 WLANs can be traced back to the Physical layer.

Question 22

What can cause PSK authentication to fail? (Choose all that apply.) 3

A. Passphrase mismatch
B. Expired root CA certificate
C. WLAN client driver problem
D. Expired LDAP user account
E. Encryption mismatch

Answer 22

A. Passphrase mismatch
C. WLAN client driver problem
E. Encryption mismatch

Expiration is excluded

Question 23

When the Wi-Fi network is the actual source of a connectivity, security, or performance problem, which WLAN device is usually where the problem resides?

A. WLAN controller
B. Access point
C. WLAN client
D. Wireless network management server

Answer 23

C. WLAN client

Question 24

What are some problems that can occur when an indoor access point is transmitting at full power? (Choose all that apply.) 3

A. Hidden node
B. Co-channel interference
C. Sticky clients
D. Intersymbol interference
E. Band hopping

Answer 24

A. Hidden node
B. Co-channel interference
C. Sticky clients

Question 25

A single user is complaining that their VoWiFi phone has choppy audio. The WLAN administrator notices that the user’s MAC address has a retry rate of 25 percent when observed with a protocol analyzer. However, all the other users have a retry rate of about 5 percent when also observed with the protocol analyzer. What is the most likely cause of this problem?

A. Near/far
B. Multipath
C. Co-channel interference
D. Hidden node
E. Low SNR

Answer 25

D. Hidden node

Question 26

The WLAN administrator is trying to explain to his boss that the WLAN is not the reason that Andrew’s boss cannot post on Facebook. Andrew has determined that the problem does not exist at layer 1 or layer 2 of the OSI model. What should Andrew say to his boss? (Choose the best answer.)

A. Wi-Fi operates only at layer 1 and layer 2 of the OSI model. The WLAN is not the problem.
B. The problem is most likely a networking problem or an application problem.
C. Do not worry, boss; I will fix it.
D. Why are you looking at Facebook during business hours?

Answer 26

C. Do not worry, boss; I will fix it.

Question 27

What are some of the negative effects of layer 2 retransmissions? (Choose all that apply.)

A. Decreased range
B. Excessive MAC sublayer overhead
C. Decreased latency
D. Increased latency
E. Jitter

Answer 27

B. Excessive MAC sublayer overhead
D. Increased latency
E. Jitter

Question 28

You have been tasked with troubleshooting a client connectivity problem at your company’s headquarters. All the APs and employee iPads are configured for PSK authentication. An employee notices that they cannot connect their iPad to the AP in the reception area of the main building but can connect to other APs. View the following graphic and describe the cause of the problem.

A. The WLAN client driver is not communicating properly with the device’s OS.
B. The APs are configured for CCMP encryption only. The client only supports TKIP.
C. The client has been configured with the wrong WPA2-Personal passphrase.
D. The AP in the reception area has been configured with the wrong WPA2-Personal passphrase.

Answer 28

D. The AP in the reception area has been configured with the wrong WPA2-Personal passphrase.

Question 29

You have been tasked with configuring a secure WLAN for 400 APs at the corporate offices. All the APs and employee Windows laptops have been configured for 802.1X/EAP using PEAPv0 (EAP-MSCHAPv2). The domain user accounts are failing authentication with every attempt. Determine the possible causes of the problem. (Choose all that apply.)

A. The networking settings on the AP are incorrect.
B. The supplicant clock settings are incorrect.
C. An authentication port mismatch exists between the AP and the RADIUS server.
D. The networking settings on the RADIUS server are incorrect.
E. The incorrect root certificate is selected in the supplicant.
F. The root certificate has expired.

Answer 29

B. The supplicant clock settings are incorrect.
E. The incorrect root certificate is selected in the supplicant.
F. The root certificate has expired.

Root certs and clock

Question 30

The network administrator of the WonderPuppy Coffee Company calls the support hotline for his WLAN vendor and informs the support personnel that the WLAN is broken. The support personnel ask the customer a series of questions so that they can isolate and identify the cause of a potential problem. What are some common Troubleshooting 101 questions? (Choose all that apply.)

A. When is the problem happening?
B. What is your favorite color?
C. What is your quest?
D. Does the problem reoccur or did it just happen once?
E. Did you make any changes recently?

Answer 30

A. When is the problem happening?
D. Does the problem reoccur or did it just happen once?
E. Did you make any changes recently?

Question 31

The corporate IT administrators are huddled together to try to solve an issue with the newly deployed VoWiFi phones. …
What are the possible causes of the interruption of service for the voice calls while the employees are mobile? (Choose all that apply.) 2

A. VoWiFi phones should be configured only for PSK authentication when roaming is a requirement.
B. VoWiFi phones are reauthenticating every time they roam to a new AP.
C. VoWiFi phones do not use opportunistic key caching.
D. VoWiFi phones do not support fast BSS transition.

Answer 31

B. VoWiFi phones are reauthenticating every time they roam to a new AP.
D. VoWiFi phones do not support fast BSS transition.

Question 32

Which of the following are the two most likely causes of roaming problems? (Choose all that apply.) 2

A. Not enough secondary coverage
B. Too much secondary coverage
C. Co-channel interference
D. Adjacent cell interference
E. Hidden node

Answer 32

A. Not enough secondary coverage
B. Too much secondary coverage

Question 33

Professor Perry Correll has an Ethernet switch that is compliant with 802.3at. He is having problems with his APs randomly rebooting. Which of the following could be causing his problems?

A. Multiple desktop PoE VoIP telephones are connected to the same Ethernet switch.
B. Most of the Ethernet cables running from the switch to the APs are 90 meters long.
C. The Ethernet cables are only Cat 5e.
D. The switch is capable of 1000BaseT, which is not compatible with the AP.

Answer 33

A. Multiple desktop PoE VoIP telephones are connected to the same Ethernet switch.

Question 34

Which Windows CLI command can display a WLAN client’s authentication method, encryption method, channel, signal
strength, and data rate?

A. netsh wlan show drivers
B. airport -S
C. netsh wlan show interfaces
D. airport -I
E. nslookup
F. traceroute

Answer 34

C. netsh wlan show interfaces

Question 35

The network administrator of the Holy Grail Corporation calls the support hotline for his WLAN vendor and informs the support personnel that the WLAN is no longer working. The support personnel ask the customer a series of questions so that they can isolate and identify the cause of a potential problem. What are some ommon Troubleshooting 101 questions?
(Choose all that apply.)

A. When is the problem happening?
B. Where is the problem happening?
C. Does the problem affect one client or numerous clients?
D. What is the airspeed velocity of an unladen swallow?

Answer 35

A. When is the problem happening?
B. Where is the problem happening?
C. Does the problem affect one client or numerous clients?

Question 36

WLAN administrator Marko Tisler is troubleshooting an IPsec VPN problem between a remote WLAN branch router and a VPN gateway server at corporate headquarters. Marko cannot get the VPN tunnel to establish and notices that there is a certificate error during the IKE Phase 1 exchange. What are the possible causes of this problem? (Choose all that apply.) 2

A. The VPN server at corporate headquarters is using AES-256 encryption, and the remote WLAN branch router is using AES-192 encryption.
B. The VPN server at corporate headquarters is using SHA-1 hash for data integrity, and the remote WLAN branch router is using MD5 for data integrity.
C. The root CA certificate installed on the VPN remote WLAN branch router was not used to sign the server certificate on the corporate VPN server.
D. The clock settings of the corporate VPN server predate the creation of the server certificate.
E. The public/private IP address settings are misconfigured on the remote WLAN branch
router.

Answer 36

C. The root CA certificate installed on the VPN remote WLAN branch router was not used
D. The clock settings of the corporate VPN server predate the creation of the server certificate.

Question 37

You have been tasked with configuring a secure WLAN for 600 APs at the corporate offices. All the APs and the Google Chromebook employee laptops have been configured for PEAPv0 (EAP-MSCHAPv2). Connectivity is failing for one of the employee laptops. After viewing the graphic shown here, determine the possible causes of the problem. (Choose all that apply.) 2

A. The VLAN on the access layer switch is incorrectly configured.
B. The machine accounts were not joined to the domain.
C. The server certificate has expired.
D. The supplicant has been configured only for user authentication.
E. The root certificate has expired.
F. The DHCP server has run out of leases.

Answer 37

A. The VLAN on the access layer switch is incorrectly configured.
F. The DHCP server has run out of leases.

Question 38

What can be done to fix the hidden node problem? (Choose the best answer.)

A. Increase the power on the access point.
B. Move the hidden node station.
C. Decrease power on all client stations.
D. Remove the obstacle.
E. Decrease power on the hidden node station.
F. Add another AP.

Answer 38

F. Add another AP.

Question 39

Layer 2 retransmissions occur when frames become corrupted. What are some of the causes of layer 2 retransmissions? (Choose all that apply.)

A. High SNR
B. Low SNR
C. Co-channel interference
D. RF interference
E. Adjacent channel interference

Answer 39

B. Low SNR
D. RF interference
E. Adjacent channel interference

Question 40

When you are troubleshooting client connectivity problems with a client using 802.1X/EAP security, what is the first action you should take to investigate a potential layer 1 problem?

A. Reboot the WLAN client.
B. Verify the root CA certificate.
C. Verify the EAP protocol.
D. Disable and reenable the client radio network interface.
E. Verify the server certificate.

Answer 40

D. Disable and reenable the client radio network interface.

Question 41

Which of the following modulation methods are supported with 802.11ac? (Choose all that apply.)

A. BPSK
B. BASK
C. 1024-QAM
D. 64-QAM
E. 256-QAM

Answer 41

A. BPSK
D. 64-QAM
E. 256-QAM

Question 42

How can a MIMO system increase throughput at the Physical layer? (Choose all that apply.)

A. Spatial multiplexing
B. A-MPDU
C. Transmit beamforming
D. 40 MHz channels

Answer 42

A. Spatial multiplexing
C. Transmit beamforming
D. 40 MHz channels

Question 43

Which power-management method defined by the 802.11n amendment conserves power by powering down all but one radio?

A. A-MPDU
B. Power Save protection
C. PSMP
D. SM power save
E. PS mode

Answer 43

D. SM power save

Question 44

The guard interval is used as a buffer to compensate for which type of interference?

A. Co-channel interference
B. Adjacent cell interference
C. RF interference
D. HT interference
E. Intersymbol interference

Answer 44

E. Intersymbol interference

Question 45

Which of the following channel widths are supported in 802.11ac? (Choose all that apply.) hint, hint

A. 20 MHz
B. 40 MHz
C. 80 MHz
D. 80+80 MHz
E. 160 MHz

Answer 45

All of these are supported channel widths. The 160 MHz channel is actually made up of two 80 MHz channels, which can be side by side or separated.

Question 46

What could an 802.11n (HT) radio use to increase throughput at the MAC sublayer of the Data-Link layer? (Choose all that apply.)

A. A-MSDU
B. A-MPDU
C. Guard interval
D. Block ACKs
E. Spatial multiplexing

Answer 46

A. A-MSDU
B. A-MPDU
D. Block ACKs

Question 47

Which of the following technologies is part of explicit beamforming? (Choose all that apply.)

A. Channel sounding
B. Feedback matrix
C. Sounding matrix
D. Steering matrix
E. Null data packet
F. Channel matrix

Answer 47

B. Feedback matrix
D. Steering matrix
E. Null data packet

Question 48

A 3×3:2 MIMO radio can transmit and receive how many unique streams of data?

A. Two
B. Three
C. Four
D. Five
E. None—the streams are not unique data

Answer 48

A. Two

Question 49

Name a capability not defined for A-MPDU.

A. Multiple QoS access categories
B. Independent data payload encryption
C. Individual MPDUs having the same receiver address
D. MPDU aggregation

Answer 49

A. Multiple QoS access categories

Question 50

Which HT protection modes would allow only for the association of 802.11a/g clients to an 802.11ac access point? (Choose all that apply.) 1

A. Mode 0—Greenfield mode
B. Mode 1—HT nonmember protection mode
C. Mode 2—HT 20 MHz protection mode
D. Mode 3—HT Mixed mode

Answer 50

D. Mode 3—HT Mixed mode

Question 51

Which of these statements are true about 40 MHz channels? (Choose all that apply.)

A. 802.11 management and control frames are transmitted only on the primary channel.
B. 802.11n/ac data frames can be sent together on the primary and secondary channels.
C. 802.11 management and control frames are transmitted only on the secondary
channel.
D. 802.11 data frames sent by an 802.11g client are sent on the secondary channel.
E. 802.11 data frames sent by an 802.11g client are sent on the primary channel.

Answer 51

A. 802.11 management and control frames are transmitted only on the primary channel.
B. 802.11n/ac data frames can be sent together on the primary and secondary channels.
E. 802.11 data frames sent by an 802.11g client are sent on the primary channel.

Primary, primary, secondary & primary

Question 52

MIMO radios use which mechanisms for transmit diversity? (Choose all that apply.)

E. Spatial multiplexing (SM)
A. Maximal ratio combining (MRC)
D. Cyclic shift diversity (CSD)
B. Direct-sequence spread spectrum (DSSS)
C. Space-time block coding (STBC)

Answer 52

C. Space-time block coding (STBC)
D. Cyclic shift diversity (CSD)
E. Spatial multiplexing (SM)

Question 53

802.11n (HT) radios are backward compatible with which of the following types of 802.11 radios? (Choose all that apply.) 3

A. 802.11b radios (HR-DSSS)
B. 802.11a radios (OFDM)
C. 802.11 legacy radios (FHSS)
D. 802.11g radios (ERP)

Answer 53

A. 802.11b radios (HR-DSSS)
B. 802.11a radios (OFDM)
D. 802.11g radios (ERP)

No FHSS–n is not compatible with legacy radios.

Question 54

How many modulation and coding schemes are defined in 802.11ac?

A. 8
B. 10
C. 64
D. 77
E. 256

Answer 54

B. 10

Question 55

Which 802.11ac MCS range defines all of the MCSs that are mandatory for Wi-Fi certification?

A. MCS 0–2
B. MCS 0–4
C. MCS 0–6
D. MCS 0–7
E. MCS 0–8
F. MCS 0–9

Answer 55

D. MCS 0–7

Question 56

Braydon, a WLAN consultant, has recommended that a new 802.11n/ac network use only 40 MHz channels in the 5 GHz U-NII bands. Why would he recommend that 40 MHz channels be used only in 5 GHz and not in 2.4 GHz?

A. HT/VHT radios do not require DFS and TPC in the 5 GHz bands.
B. HT/VHT radios get better range using TxBF in the 5 GHz bands.
C. 40 MHz channels do not scale in the 2.4 GHz ISM band.
D. 5 GHz VHT radios are less expensive than 2.4 GHz HT radios.

Answer 56

C. 40 MHz channels do not scale in the 2.4 GHz ISM band.

Question 57

802.11ac (VHT) radios are backward compatible with which of the following types of 802.11 technology? (Choose all that apply.)

A. 802.11b (HR-DSSS)
B. 802.11a (OFDM)
C. 802.11g (ERP)
D. 802.11n (HT)

Answer 57

B. 802.11a (OFDM)
D. 802.11n (HT)

Question 58

Which of these methods of MIMO receive diversity is useful when receiving incoming transmissions from a SISO radio?

A. Space-time block coding (STBC)
B. Maximal ratio combining (MRC)
C. Transmit beamforming (TxBF)
D. Spatial multiplexing (SM)

Answer 58

B. Maximal ratio combining (MRC)

Question 59

Which PHY layer mechanism might be used to increase throughput for an HT/VHT radio in a clean RF environment with minimal reflections and low multipath?

A. Maximal ratio combining
B. 400-nanosecond guard interval
C. Switched diversity
D. Spatial multiplexing
E. Spatial diversity

Answer 59

B. 400-nanosecond guard interval

Question 60

The 802.11ac amendment defines a maximum of how many spatial streams for a client?

A. One
B. Two
C. Four
D. Eight

Answer 60

C. Four