CWNA-106 Certified Wireless Network Administrator Questions and Answers

Short guard intervals

DTIM Interval

Listen Interval

Probe Request frames

RTS or CTS frames

Diffraction

Reflection

Refraction

Diffusion

Scattering

The data throughput rate will increase because VSWR will decrease.

The Equivalent Isotropically Radiated Power (EIRP) will decrease.

The antenna’s azimuth beamwidth will decrease.

The size of the Fresnel zone will increase.

The likelihood of a direct lightning strike will increase.

Fade Margin is an additional pad of signal strength designed into the RF system to compensate for unpredictable signal fading.

The Fade Margin of a long-distance radio link should be equivalent to the receiver’s antenna gain.

A Fade Margin is unnecessary on a long-distance RF link if more than 80% of the first Fresnel zone is clear of obstructions.

The Fade Margin is a measurement of signal loss through free space, and is a function of frequency and distance.

Client devices ignore the TIM field and automatically send PS-Poll frames after every beacon.

After each beacon, the AP attempts to empty its frame buffer by sending Wake-on-WLAN frames to wake each dozing client.

Request-to-Send and Clear-to-Send frame exchanges are used to trigger the delivery of buffered data.

The Beacon interval is changed from the default 100 time units to 10 or less time units.

Clients send null data frames to the AP and switch the power management bit from 1 to 0 to receive queued data.

Stations send a CTS-to-self frame to the AP with a very long duration period so they can receive all of their buffered data at once.

Introduces “fast transition” roaming protocols for VoWiFi phones

Better link reliability between 802.11a/b/g client devices and 802.11ac APs

Improves service quality for real-time applications at greater distances

Increases in receive sensitivity enhance RTLS location accuracy

Stronger security with more robust encryption modes.

Use of larger frame sizes results in greater throughput in low interference environments.

BSS support for 65 KB A-MPDUs will increase the maximum data rate available to client devices.

In 802.11ac, changing the security mechanism from WPA2-Personal to WPA2-Enterprise will enable the VHT MCS rates.

Compared to an Independent BSS, an Infrastructure BSS can provide almost twice the throughput between wireless nodes.

Use of short guard intervals improves reliability and throughput in high multipath environments

Microwave ovens

Narrow hallways

Elevator shafts

RFID chokepoints

Workspace dividers

The direct signal will only be received if the reflected signal is more than 180 degrees out of phase.

The direct signal cannot be received if the indirect signal is less than 90 degrees out-of-phase.

The signals will be distorted if the indirect signal arrives simultaneously at the receiver, but 90 degrees out-of-phase.

If the signals are in-phase, they will combine together, cancel one another out, and create a null.

The RF interference caused by passing airplanes supporting on-board Wi-Fi should be a prime consideration.

The omni-directional antennas of the access points should be oriented parallel to the floor to maximize the coverage pattern across as many floors as possible.

The channel reuse pattern should be three dimensional with the RF cell extending coverage of each access point to other floors.

The Fresnel Zone is completely blocked between floors so each floor is considered a separate site survey.

HT

OFDM

HR/DSSS

ERP-PBCC

DSSS-OFDM

802.11ad compatibility

TPC support

Impedance in Ohms

Elevation Beamwidth

Return Loss Rating

Operating Frequencies

The current AP is using channel 1 and the new AP is using channel 40.

The SSID of the current AP does not match the SSID of the new AP.

The current AP supports only HT and the new AP is VHT capable.

The access points are hiding the SSID in Beacons and Probe Response frames.

Client stations would see two different sets of AP capabilities as they roam between APs with the same BSSID.

The added range of 802.11n APs would cause additional co-channel interference.

The additional beacon material in 802.11n beacons would confuse 802.11b/g client stations.

Beacons from 802.11n APs use 40 MHz channels, while beacons from 802.11g APs use 20 MHz channels.

Data frames too large for the physical environment

Client stations broadcasting with too much power

Access points broadcasting with too little power

Client stations too close in proximity to each other

Obstacles between client stations causing attenuation

Large 802.11 cells with physically distributed stations