Practice Free CWNA-109 Exam Online Questions
When compared with legacy Power Save mode, how does VHT TXOP power save improve battery life for devices on a WLAN?
- A . Legacy Power Save mode was removed in the 802.11ac amendment.
- B . VHT TXOP power save allows the WLAN transceiver to disable more components when in a low power state.
- C . VHT TXOP power save uses the partial AID in the preamble to allow clients to identify frames targeted for them.
- D . VHT TXOP power save allows stations to enter sleep mode and legacy Power Save does not.
B
Explanation:
VHT TXOP (Very High Throughput Transmit Opportunity) power save is a feature introduced with the 802.11ac amendment, which is designed to improve the power efficiency of devices connected to a WLAN. This feature enhances battery life in several ways, compared to the legacy Power Save mode: Enhanced Power Saving: VHT TXOP power save allows devices to disable more components of the WLAN transceiver when they are in a low power state. This reduces the power consumption during periods when the device is not actively transmitting or receiving data.
Intelligent Wake-Up Mechanisms: It employs more sophisticated mechanisms for devices to determine when they need to wake up and listen to the channel, further reducing unnecessary power usage.
Optimized Operation: This power save mode is optimized for the high-throughput environment of 802.11ac networks, allowing devices to efficiently manage power while maintaining high performance.
Legacy Power Save mode, introduced in earlier versions of the 802.11 standards, does not provide the same level of component disablement or the intelligent wake-up mechanisms found in VHT TXOP power save, making option B the correct answer.
Reference: IEEE 802.11ac-2013 Amendment: Enhancements for Very High Throughput for Operation in Bands below 6 GHz.
CWNA Certified Wireless Network Administrator Official Study Guide: Exam CWNA-109, by David D.
Coleman and David A. Westcott.
What term correctly completes the following sentence? In an IEEE 802.11 frame, the IP packet is considered by the MAC layer to be a(n) _________.
- A . MAC Service Data Unit (MSDU)
- B . MAC Protocol Data Unit (MPDU)
- C . IP datagram
- D . PLCP Service Data Unit (PSDU)
- E . PLCP Protocol Data Unit (PPDU)
Which of the following encryption methods use symmetric ciphers? (Choose all that apply.)
- A . WEP
- B . TKIP
- C . Public-key cryptography
- D . CCMP
Which value should not be used to compare wireless network cards manufactured by different WLAN vendors?
- A . Receive sensitivity
- B . Transmit power range
- C . Antenna dBi
- D . RSSI
A WLAN consultant has recommend that a new 802.11n HT network be deployed by using channels in the 5 GHz U-NII bands.
Why would he recommend 5 GHz over 2.4 GHz?
- A . HT radios do not require DFS and TPC in the 5 GHz bands.
- B . HT 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 HT radios are less expensive than 2.4 GHz HT radios.
WMM-PS is based on which 802.11-2012 power-management method?
- A . S-APSD
- B . U-APSD
- C . PSMP
- D . SM Power Save
- E . PS-Poll
Which sublayer of the OSI model’s Data-Link layer is used for communication between 802.11 radios?
- A . LLC
- B . WPA
- C . MAC
- D . FSK
A wireless bridge is configured to transmit at 100 mW. The antenna cable and connectors produce a 3 dB loss and are connected to a 16 dBi antenna.
What is the EIRP?
- A . 20 mW
- B . 30 dBm
- C . 2,000 mW
- D . 36 dBm
- E . 8 W
Which of these attacks can be mitigated with a mutual authentication solution? (Choose all that apply.)
- A . Malicious eavesdropping
- B . Deauthentication
- C . Man-in-the-middle
- D . Wireless hijacking
- E . Authentication flood
What fact is true regarding controllers and Aps in a split-MAC architecture?
- A . Using centralized data forwarding, frames leaving the Aps are never tagged Ethernet frames with VLAN identifiers
- B . An IP tunnel is established between the AP and controller for AP management and control functions
- C . With 802.1X/EAP security, the AP acts as the supplicant and the controller acts as the authenticator
- D . Management and data frames must be processed locally by the AP, while control frames are sent to the controller