Question 1

Which of the following is an advantage of the 5 GHz, 802.11a equipment over a 2.4 GHz, 802.11b equipment?

Accepted Answer

The 5 GHz UNII bands allows for more non-overlapping channels than the 2.4 GHz ISM band.
Key Takeaway: The lower portion of the 5 GHz UNII band and the 2.4 GHz ISM band are the same width of about 100 MHz. The UNII bands allow a larger useable portion than the 2.4 GHz ISM band. Hence, it yields a maximum of 4 non-overlapping DSSS channels.

Question 2

Which of the following must be used to provide continuous connectivity when a client station is roaming across layer 3 boundaries?

Accepted Answer

You should provide the proprietary layer 3 roaming solution to ensure continuous connectivity when a client station is roaming across layer 3 boundaries.
Key Takeaway: Layer 3 mobility is a superset of Layer 2 mobility. An 802.11 client must perform a Layer 2 roam, including AP discovery, before it can begin a Layer 3 roam. A wireless client can only roam between APs in the same VLAN and with the same SSID. As WLAN deployments expand within an organization, roaming domains might need to scale beyond a single Layer 2 VLAN. The only way to maintain upper-layer communications when crossing layer 3 subnets is to provide either a Mobile IP solution or a proprietary layer 3 roaming solution.

Question 3

Which of the following methods should be used to set the threshold when using RTS/CTS in "On with Threshold" mode on a wireless LAN?

Accepted Answer

You should manually set the threshold on the clients and access points when using RTS/CTS in "On with Threshold" mode on a wireless LAN.
Key Takeaway: RTS/CTS, or Request to Send/Clear to Send, is an optional mechanism used by the 802.11 wireless networking protocol to reduce frame collisions introduced by the hidden terminal problem. You should manually configure the access points and clients to use RTS/CTS. The three settings available with RTS/CTS are Off, On, and On with Threshold. The Off setting is used by default to reduce unnecessary overhead on the network.

Question 4

A client on the Wireless network who is farther away from the access point and using less power is masked by a client who is closer to the access point and using high power. What is this condition called?

Accepted Answer

This condition is known as Near/Far.
Key Takeaway: All client stations have a fixed power output. However, in some cases, a low-powered client station that is a great distance from the access point could potentially become an unheard client if other high powered stations are very close to the access point. The transmissions of the high-powered stations can raise the noise floor to a higher level that would prevent the lower-powered station from being heard. This condition is referred to as Near/Far condition.

Question 5

Which of the following specifies why you are able to co-locate 3 DSSS access points in the same area using the 2.4 GHz ISM band?

Accepted Answer

You should be able to co-locate 3 DSSS access points in the same area using the 2.4 GHz ISM band because each access point will use channels that do not overlap or cause adjacent channel interference.
Key Takeaway: There are three non-overlapping DSSS channels specified by the FCC in the 2.4 GHz ISM band. Each of these bands is separated by a frequency of 5 MHz. These channels are 1, 6, and 11.

Question 6

In a network setup a set of access points are connected to the wired segment. Your key objective is to extend the range of the access points to clients who are outside the range of the access points in the wired segment. So you connected interconnect the access points in the some other access points wirelessly.. Which mode will the access point not connected to the wired LAN segment use?

Accepted Answer

The access point that is not connected to the wired LAN segment will use the Repeater mode.
Key Takeaway: Repeater mode extends the wireless segment to users who cannot see the access point connected to the wired LAN. It is also used when an additional access point cannot be connected to the wired infrastructure in a particular area.

Question 7

Which of the following specifies the function of a wireless bridge?

Accepted Answer

The wireless bridge is used for point-to-multipoint configurations.
Key Takeaway: The two basic configurations using wireless bridges include point-to-point and point-to-multipoint. You can configure a building-to-building bridging link using either of these configurations.

Question 8

Which of the following wireless client devices is not a plug-n-play device?

Accepted Answer

An ISA Card is not a plug-n-play device.
Key Takeaway:- Wireless ISA devices do not support plug-n-play functionality. They have to be configured manually. Legacy 9-pin serial wireless client devices do not support plug-n-play configuration. PCI, PCMCIA, CF, and USB devices support plug-n-play configuration.

Question 9

You discover that some coaxial cables connected to the company's outdoor wireless bridges are damaged. You replace the cabling, but soon discover that the EIRP leaving the bridge antenna now exceeds the power output limit. Which of the following is the most likely cause of this issue?

Accepted Answer

The most likely cause of this issue is that you have installed higher-grade cabling.
Key Takeaway: The Effective Isotropic Radiated Power, or EIRP, is the apparent power transmitted towards the receiver if the signal is radiated equally in all directions as a spherical wave emanating from a point source. If you have installed a higher-grade cable that is rated for lesser loss per 100 feet, it could exceed power output regulations.

Question 10

Which of the following can be used to mitigate issues arising due to the near/far condition?

Accepted Answer

To mitigate issues arising due to the near/far condition, increase the power of remote stations.
Key Takeaway: The transmission levels of high-powered stations could raise the noise floor to a higher level. Hence, the lower powered station cannot be heard. Increasing the power of the remote station and/or decreasing the power of the near stations will help in better listening to the remote stations.

Question 11

Concentric zones of variable rate bandwidth coverage exist around an access point due to the up shifting and down shifting of client radio cards between data rates. Which of the following specifies this process?

Accepted Answer

This process is called dynamic rate switching
Key Takeaway: When a client station radio moves away from an access point, it shifts down to lower bandwidth capabilities using a process known as dynamic rate switching, or DRS. DRS up shifts and down shifts data rates for optimization and improved performance.

Question 12

What is the interval between the main wave's arrival at the receiver and the reflected wave's arrival at a receiver called?

Accepted Answer

The interval between the main wave's arrival at the receiver and the reflected wave'; arrival at a receiver is called Delay spread.
Key Takeaway: Delay spread is the interval between when the main RF wave arrives at the receiver and the last reflected wave arrives at the receiver. This value is typically 4 nanoseconds or less.

Question 13

Which of the following can cause issues associated with roaming?

Accepted Answer

Very small cell coverage overlap cause issues associated with roaming.
Key Takeaway: Roaming problems occur if there is very small overlap in cell coverage. Very small overlap creates a roaming dead zone and connectivity may even be lost temporarily. If two RF cells have too much overlap, a station may stay associated with its original AP and not connect to a second access point even though the station is directly underneath the second access point.

Question 14

Why are most of the access points built with two antennas?

Accepted Answer

Access points are built with two antennas to overcome multipath.
Key Takeaway: Access points use two antennas to implement antenna diversity and overcome multipath. Multipath is caused by reflected RF waves and can disrupt or corrupt data transmissions. Access points sample inputs from both antennas and use the best signal. Access points normally transmit on the antenna last used for receiving.

Question 15

Which of the following best defines Multipath?

Accepted Answer

Multipath is a set of negative effects induced on a wireless LAN by reflected RF signals arriving at the receiver along with the main signal.
Key Takeaway: Multipath is the set of negative effects on a wireless LAN that is a result of multiple RF signals arriving at the same destination at almost the same time from the same source. Multipath is disruptive when there are reflective objects in the signal path from the transmitter to the receiver.

Question 16

Why should you disable the two lowest rates on an 802.11b/g access point?

Accepted Answer

You should disable the two lowest rates on an 802.11b/g access point to enable hidden nodes to hear stations at the other end of coverage cell.
Key Takeaway: Radio cards transmitting at slower data rates will occupy the medium much longer. Data transmitted at rates of 1 and 2 Mbps can create very large coverage cells. This prevents a hidden node station at one edge of the cell from being heard by other client stations at the opposite side of the coverage cell.

Question 17

Which of the following can be done to fix the hidden node problem?

Accepted Answer

To fix the hidden node problem, you should move the hidden node station within transmission range of the other stations.
Key Takeaway: The hidden node problem arises when client stations cannot hear the RF transmissions of another client station. Increasing the transmission power of client stations will increase the transmission range of each station, resulting in increased likelihood of all the stations hearing each other. Moving the hidden node station within transmission range of the other stations also results in stations hearing each other.

Question 18

Which of the following is not a criterion for WEP implementation, as per the 802.11 standard?

Accepted Answer

As per the 802.11 standard, the use of WEP as an encryption standard is optional.
Key Takeaway: In case a manufacturer makes the hardware compliant the standard, the administrator must be able to enable or disable WEP as necessary.

Question 19

Which of the following is a key rotation option implemented by various manufacturers for encryption key generation?

Accepted Answer

Per-packet is the key rotation option implemented by various manufacturers for encryption key generation.
Key Takeaway: Most centralized encryption key servers have the ability to implement key rotation on a per-packet or a per-session basis. You should not add more overhead to the network than the network can withstand when implementing per-packet key rotation.

Question 20

Which of the following is the level of encryption when using a WEP key with a 40-bit secret key concatenated with the initialization vector to form the WEP key?

Accepted Answer

The level of encryption when using a WEP key using a 40-bit secret key concatenated with the initialization vector to form the WEP key is 64-bit.
Key Takeaway: The initialization vector, or IV, is a 24-bit number used to start and track the wireless frames moving between nodes. IV is concatenated with the secret key to yield the WEP key. The 64-bit WEP key is generated with a 40-bit secret key added to a 24-bit IV.

Quiz 1: Certified Wireless Network Administrator (CWNA)