Practice Free CWNA-109 Exam Online Questions
128-bit WEP encryption uses a user-provided static key of what size?
- A . 104 bytes
- B . 64 bits
- C . 124 bits
- D . 128 bits
- E . 104 bits
When using a spectrum to look for non Wi-Fi interference sources, you notice significant interference across the entire 2.4 GHz band (not on a few select frequencies) within the desktop area of a users workspace, but the interference disappears quickly after just 2 meters.
What is the most likely cause of this interference?
- A . USB 3 devices in the user’s work area
- B . Bluetooth devices in the user’s work area
- C . Excess RF energy from a nearby AP
- D . Unintentional radiation from the PC power supply
A
Explanation:
USB 3 devices in the user’s work area are the most likely cause of this interference when using a spectrum analyzer to look for non-Wi-Fi interference sources. A spectrum analyzer is a tool that measures and visualizes the radio frequency activity and interference in the wireless environment. A spectrum analyzer can show the spectrum usage and energy levels on each frequency band or channel and help identify and locate the sources of interference. Interference is any unwanted signal that disrupts or degrades the intended signal on a wireless channel. Interference can be caused by various sources, such as other Wi-Fi devices, non-Wi-Fi devices, or natural phenomena. Interference can affect WLAN performance and quality by causing signal loss, noise, distortion, or errors. USB 3 devices are non-Wi-Fi devices that use USB 3.0 technology to transfer data at high speeds between computers and peripherals, such as hard drives, flash drives, cameras, or printers. USB 3 devices can generate electromagnetic radiation that interferes with Wi-Fi signals in the 2.4 GHz band, especially when they are close to Wi-Fi devices or antennas. USB 3 devices can cause significant interference across the entire 2.4 GHz band (not on a few select frequencies) within the desktop area of a user’s workspace, but the interference disappears quickly after just 2 meters. This is because USB 3 devices emit broadband interference that affects all channels in the 2.4 GHz band with a high intensity near the source but a low intensity at a distance due to attenuation. The other options are not likely to cause this interference pattern when using a spectrum analyzer to look for non-Wi-Fi interference sources. Bluetooth devices in the user’s work area are non-Wi-Fi devices that use Bluetooth technology to communicate wirelessly between computers and peripherals, such as keyboards, mice, headphones, or speakers. Bluetooth devices can cause interference with Wi-Fi signals in the 2.4 GHz band, but they use frequency hopping spread spectrum (FHSS) technique that changes frequencies rapidly and randomly within a range of 79 channels. Therefore, Bluetooth devices do not cause significant interference across the entire 2.4 GHz band (not on a few select frequencies), but rather intermittent interference on some channels at different times. Excess RF energy from a nearby AP is not a non-Wi-Fi interference source but rather a Wi-Fi interference source that occurs when an AP transmits more power than necessary for its coverage area. Excess RF energy from a nearby AP can cause co-channel interference (CCI) with other APs or client devices that use the same channel within range of each other. CCI reduces performance and capacity because it causes contention and collisions on the wireless medium,
Which protocols are used to transport 802.11 frames between a controller-based AP and a WLAN controller? (Choose all that apply.)
- A . GRE
- B . CCMP
- C . Mobile IP
- D . CAPWAP
- E . Proprietary IP tunneling protocols
- F . All of the above
What component of the 802.11 standard allows stations to reserve access to the RF medium for a specified period of time?
- A . Short guard intervals
- B . DTIM Interval
- C . Listen Interval
- D . Probe Request frames
- E . RTS or CTS frames
You administer a small WLAN with nine access points. As a small business, you do not run a RADIUS server and use WPA2-Personal for security.
Recently, you changed the passphrase for WPA2-Personal in all APs and clients. Several users are now reporting the inability to connect to the network at times and it is constrained to one area of the building.
When using a WLAN scanner, you see that the AP covering that area is online and has a strong signal. No other changes have been made to the environment and all access points are the same model.
What is the likely problem?
- A . The AP that covers the problem area requires a firmware update
- B . The clients are improperly configured
- C . The AP that covers the problem area has failed
- D . The AP that covers the problem area is improperly configured
What distinguishes an independent basic service set (IBSS) from an infrastructure basic service set (BSS)?
- A . An IBSS does not have a distribution system (DS), but a BSS does.
- B . An IBSS does not require beacon frames, but a BSS does.
- C . An IBSS does not support 802.11 authentication or association, but a BSS does.
- D . An IBSS does not support any 802.11ac enhancements, but a BSS does.
What factors need to be considered when planning for capacity and coverage in a 5 GHz WLAN? (Choose all that apply.)
- A . Data applications
- B . User density
- C . Peak usage level
- D . DFS channels
George is designing an 802.3at-capable network and is installing a 24-port Ethernet switch to support 10 Class 2 cameras and 10 Class 3 APs. The switch requires 1,000 watts to perform its basic switching functions.
How much total power will be needed?
- A . 1,080 watts
- B . 1,224 watts
- C . 1,308 watts
- D . 1,500 watts
What are some of the key differences and advantages of OFDMA over MU-MIMO with 802.11ax radios? (Choose all that apply.)
- A . Increased efficiency
- B . Increased capacity
- C . Best for high-bandwidth applications
- D . Best for low-bandwidth applications
- E . Best with small packets
- F . Best with large packets
What wireless networking term describes the increase of RF energy in an intentional direction with the use of an antenna?
- A . Directed Radiation
- B . Active Amplification
- C . Passive Gain
- D . Beam Digression