PW0-250 Online Practice Questions and Answers

In a centralized WLAN architecture, what new problem may arise when you change the data forwarding model from centralized to distributed? (Choose 2)

A. APs that were designed for a centralized forwarding model may not support all features in distributed forwarding mode.

B. The Ethernet switch ports to which APs are connected may need to be reconfigured to support VLAN tagging and QoS at the network edge.

C. All RRM controls will also need to be distributed to a master AP that acts as a channel and transmit power arbiter for other APs in the ESS.

D. Centralized control functions, such as key management and distribution, RRM, and load balancing will no longer be supported.

E. APs will not have the processing capabilities to support AES-CCMP, so TKIP will be the recommended encryption method.

Given: The 802.11n APs you have selected for your public access deployment support many of the PHY and MAC enhancements offered by the 802.11n standard. The AP is single-band (2.4 GHz) and only allows 20 MHz channels. The WLAN radio in the AP is a 3x3 802.11n chip that supports two spatial streams.

What is the maximum MCS rate that could be supported by this AP?

A. 54 Mbps

B. 65 Mbps

C. 108 Mbps

D. 144 Mbps

E. 150 Mbps

F. 300 Mbps

To achieve a 450 Mbps MCS, what 802.11n features (from the numbered list below) are required?

1.

Frame aggregation

2.

Short GI

3.

40 MHz channels

4.

2 spatial streams

5.

3 spatial streams

6.

Transmit beamforming (TxBF)

A. 1, 2, 3, 4

B. 1, 2, 3, 5

C. 1, 2, 3, 4, 6

D. 1, 2, 3, 5, 6

E. 2, 3, 4

F. 2, 3, 5

Given: Use the exhibit as a reference. ABC Company has a WLAN controller with 10 controller- based APs; the Voice SSID is configured for centralized data forwarding. Each AP is connected to an access port on a layer-2 Ethernet switch. Each layer-2 switch is uplinked to a single layer-3 core Ethernet switch. The WLAN controller is connected directly to the layer-3 core Ethernet switch. Layer-3 tunnels are created between all controller-based APs and the WLAN controller. A voice server is connected to the layer-3 Ethernet switch.

When a voice-enabled QoS STA sends an IP data packet to a voice server in this scenario, the DSCP value carried in the STA's IP data packet gets mapped to what and by which device?

A. The DSCP value is mapped to an IEEE 802.1Q priority tag value by the WLAN controller.

B. The DSCP value is mapped to the DSCP value in the encapsulating IP header by the layer-3 switch.

C. The DSCP value is mapped to an IEEE 802.1p (802.1D-2004) UP value by the access point.

D. The DSCP value is mapped to an IEEE 802.1Q VLAN tag by the access point.

E. The DSCP value is mapped to the VLAN ID by the layer-2 Ethernet switch.

An associated STA detects a new BSS with the same SSID as the STA's current BSS. The new BSS uses a different IP subnet than the current BSS. If the STA is configured to use 802.1X/EAP preauthentication, what is likely to occur?

A. The STA will not attempt to preauthenticate because the new BSS uses a different IP subnet.

B. The STA will attempt to preauthenticate, but fail because the new BSS uses a different data-link broadcast domain.

C. The STA will attempt to preauthenticate and succeed if DHCP is supported on the new subnet.

D. The STA will attempt to preauthenticate and succeed if IP Mobility is enabled on the AP or WLAN controller.

E. The STA will attempt to preauthenticate and succeed if the current AP has shared its cached PMK.

The exhibit illustrates the azimuth and elevation for what type of antenna?

A. Omni-directional

B. 20 degree vertical yagi

C. 120 degree horizontal sector

D. 60 degree horizontal patch

E. 10 degree vertical grid

What is a radome?

A. A type of semi-circular ceiling found in atriums and that is a heavy cause of RF reflection.

B. A weatherproof piece of plastic covering an antenna or antenna system.

C. The unit used to measure the signal reflected backward by the end of a cable.

D. A piece of metal positioned behind APs mounted on outdoor poles, designed to limit the butterfly effect.

E. The unwanted signal coverage provided by either side or back lobes in directional antennas.

Why does a frame transmitted at 1 Mbps have a greater usable range than the same frame transmitted at 54 Mbps?

A. Free space path loss causes greater signal dispersion for higher rate transmissions.

B. Receiver sensitivity requirements are lower for frames transmitted with less complex modulation and coding.

C. To improve reliability, 802.11 STAs increase transmit power as the signaling rate decreases.

D. Lower data rate RF transmissions travel at higher speeds and are less likely to experience collisions.

E. Frames sent at higher data rates are also sent at higher power levels and are therefore more prone to collisions and multipath.

Use the exhibit as a reference.

Given:

-In your regulatory domain, a Tx Power Level of "1" is equivalent to 17 dBm.

-For every integer increment (e.g. from 1 to 2) to the Tx Power Level, the AP's transmit power is halved.

In units of mW, what is the actual transmit power for an AP configured at a Tx Power Level of "4"?

A. 200 mW

B. 50 mW

C. 12.5 mW

D. 8 mW

E. 6.25 mW

F. 2.5 mW

You told your customer that multipath fading may be mitigated simply by moving one or both of the receiver's antennas a little bit, usually by one to four wavelengths away from its original position. Your customer is prepared to make the change, but does not know the wavelength for 802.11a.

What is the approximate wavelength of an 802.11a radio wave?

A. 5.5 cm (2.16 inches)

B. 12 cm (4.72 inches)

C. 15.24 cm (6 inches)

D. 45 cm (17.71 inches)

E. 58 cm (22.83 inches)

Assume that your network operates in a regulatory domain that allows use of UNII-1, UNII-2, UNII- 2e, UNII-3, and the 5.8 GHz ISM band for indoor Wi-Fi. In your upcoming 802.11n deployment, you would like to take advantage of the performance improvements that result from channel bonding. However, after extensive testing, you have determined that your mission-critical WLAN should not use channels requiring DFS support.

Given those two criteria (enable channel bonding and disable DFS channels), in the 5 GHz spectrum, how many non-overlapping channels will your system be able to use?

A. 2

B. 3

C. 4

D. 6

E. 11

Assuming an identical RF environment,

which one of these scenarios is most likely to lead to a client-to-AP link imbalance in which one- way communication results?

A. Option A

B. Option B

C. Option C

D. Option D

What exhibit reflects the recommended life-cycle steps for successfully designing and deploying an enterprise WLAN from start to finish? (Choose 2)

A. Solution 1

B. Solution 2

C. Solution 3

D. Solution 4

E. Solution 5

While configuring your site survey software for an upcoming manual survey project, you notice the configuration option for "Network Card Simu-lation" as shown in the exhibit.

A. This setting allows the site survey software to convert the AP's measured downlink RF data into a simulated data set as if the same data were transmitted by a specific client station. It is useful for determining uplink client performance when clients are located far from APs as well as projecting cell size for ad hoc networks.

B. Since WLAN adapters are not typically calibrated by manufacturers, this setting is a form of software calibration in which you can calibrate an (uncalibrated) adapter to match one of thecalibrated adapters shown in the list. This process improves the reliability of RF data collection and reporting when uncalibrated adapters are used.

C. This is the configuration area in which you specify the adapter type that will be used for the site survey so that the survey software can interpret that adapter's reported metrics (based on proprietary formulas) into an RF measurement that is standardized by the survey software and known to its users. This is done for every survey.

D. The site survey software manufacturer allows you to view the collected RF data as if it were collected by a different type of adapter. This functionality allows you to review survey data to determine how the RF environment will likely look based on the receive sensitivity and other RF capabilities of a specific client adapter.

At a university, the WLAN has been successfully deployed for ubiquitous access for faculty, students, and guests. Many student computer labs are available throughout the campus with wired network connectivity, but there are also a few smaller lab areas and workstations where Ethernet cabling is not available. For student wireless use, the students must authenticate against RADIUS/Active Directory using PEAP. Also, the network administrators at this university would like administrative access to these workstations when they are not in use by students so that the administrators can manage group policies, update OS patches, and perform other routine software maintenance.

What deployment options are available and recommended for both student use and remote administration of these workstations? (Choose 2)

A. Due to the architecture of 802.1X port-based access control, it is not possible for a wireless- only computer to access network services required by network administrators in this scenario.

B. Machine authentication accounts should be enabled to provide persistent machine network connectivity when student users are not associated.

C. The WLAN infrastructure vendor is responsible for providing proprietary client connectivity options to facilitate device connectivity without user interaction.

D. These workstations should be Ethernet-connected to a wireless client bridge, which will maintain network connectivity independent of student connectivity status.

E. These stations should be deployed with dual WLAN adapters. One adapter would be used for consistent network connectivity for administrative purposes and the second adapter should be used for student access.