CWNA Study Question

What is needed, in addition to the RADIUS server IP address and ports, to configure an AP to use a given RADIUS server? You must select 1 answer A. Shared secret B. RADIUS server MAC address C. RADIUS server host name D. VPN type used to connect to the RADIUS server

Correct Answer is:A A shared secret is entered in the RADIUS server and then entered in the AP to allow them to establish a connection. Without this, you cannot connect the AP to a secure RADIUS server.

What interframe space is used before an Ack frame? You must select 1 answer A. DIFS B. SIFS C. AIFS D. EIFS

Correct Answer is:B The short IFS (SIFS) is used before an Ack frame. It is shorter than a DIFS or AIFS and provides assurance of quick delivery of Ack frames, which is important to prevent retries that would be unnecessary.

A client STA is sending Probe Request frames on several channels. What kind of WLAN scanning is in use? You must select 1 answer A. Active scanning B. Passive scanning C. Port scanning D. Channel pruning

Correct Answer is:A Active scanning uses Probe Reqeust and Probe Response frames to locate an acceptable BSS. Passive scanning uses the content in Beacon frames to locate a BSS.

What metric or parameter is not likely to be used by a client STA when selecting a BSS to which it will connect? You must select 1 answer A. Retry rate B. RSSI C. Beacon frame signal strength D. Supported data rates

Correct Answer is:A A client STA will use metrics like RSSI and dBm signal strength related to the AP Beacon frames as well as supported data rates listed in the Beacon frames to select a qualified target BSS. The STA will not typically analyze such detailed metrics as retry rates or airtime utilization.

When multiple APs are used with a shared distribution system, such as Ethernet, what kind of WLAN service set is in use? You must select 1 answer A. ESS B. IBSS C. Ad-hoc D. Mesh BSS

Correct Answer is:A An Extended Service Set (ESS) exists when the APs can communicate with each other across a distribution system. In nearly all cases, a shared SSID is used to identify the ESS in which they participate, but other factors can be involved as well, such as shared controllers or specific infrastructure configuration options.

What may force an organization to implement a PKI for practical application in a WLAN? You must select 1 answer A. The use of EAP-TLS B. The use of PEAP C. The use of WPA2-Personal D. The use of frame aggregation

Correct Answer is:A Because many EAP types, such as EAP-TLS, rely on certificates and some depend on client certificates a PKI may be required. A PKI is comprised of certificate authorities (CAs) that either authorize other CAs to distribute certificates or generate and distribute (issue) certificates themselves. As a WLAN designer, you will have to determine whether a PKI will be available or not so that you can select the appropriate EAP type. If a constraint is in place requiring an EAP type that must have client certificates, you should be sure to document the requirement of a PKI in the design plans, though the details of the PKI can be left up to the individuals who will implement that project.

You are attempting to locate the cause of a performance problem in two WLAN cells in a mostly overlapping coverage area. You note that one AP is on channel 1 and the other is on channel 1 as well. When you document your findings, what term do you use to describe the problem in this configuration? You must select 1 answer A. CCI B. Non-Wi-Fi interference C. ACI D. ZigBee interference

Correct Answer is:A CCI exists when multiple STAs are on the same channel but connected to different APs. The APS and the client STAs can cause the CCI.

In addition to mapping IP addresses to host names for client devices, what may DNS be used for in a controller-based environment? You must select 1 answer A. Location of controllers by APs B. Configuring IP settings in client devices C. Synchronizing time clocks D. Encrypting Internet communications

Correct Answer is:A DNS is used to resolve domain names to IP addresses. It is used in WLANs to service clients for host name resolutions, but it is also used for specific WLAN functions including locating controllers. For example, when a Cisco AP receives its IP configuration from the DHCP server, if option 43 is not specified, the AP will try to resolve the DNS hostname CISCO-CAPWAP-CONTROLLER.localdomain, where localdomain is the domain configured by DHCP.

You recently configured five laptops for access to the corporate wireless network. Four of them work as expected and the fifth one stopped working yesterday. When you talk to the users, you discover that the four working laptops have suspended and resumed several times but never rebooted. The fifth non-working laptop has been rebooted. The non-connecting computer is unable to connect regardless of location. Everything else works as expected on the fifth computer. What may be causing the problem? You must select 1 answer A. Faulty new drivers on the fifth computer B. Firmware updates on the fifth computer C. Interference from non-Wi-Fi sources D. Poor signal strength

Correct Answer is:A During the reboot, an update may have been applied to the computer, including new WLAN drivers. The drivers may be faulty. It is not likely a firmware update as they are not typically delivered without manual intervention. The problem is not likely a signal strength issue as multiple locationes were attempted. For the same reason, interference is not the likely problem or it would impact the other laptops as well.

What protocol should be used for Web-based administration interfaces in order to increase security? You must select 1 answer A. HTTPS B. HTML C. HTTP D. SNMPv3

Correct Answer is:A Instead of HTTP, HTTPS should be used. HTTPS provides encryption for the link and HTTP does not. HTML is the programming language or markup language used to create web pages and SNMPv3 is a network management protocol not an administration access protocol.

What can you do to help mitigate DHCP pool depletion issues without requiring user configuration actions? You must select 1 answer A. Implement shorter lease durations B. Implement longer lease durations C. Implement smaller scopes D. Use DHCP for wired clients only and ask guests to manually configure IP settings

Correct Answer is:A Lease durations or timeouts should also be considered relative to DHCP. This is particularly important in networks where users come and go, such as guest WLANs or mobile areas of the WLAN like a lobby. Setting the lease duration to a few hours instead of a few days can reduce DHCP pool (scope) exhaustion (depletion) and allow the DHCP operations to continue.

What is the most common metric given for maximum unidirectional delay in VoIP communications? You must select 1 answer A. 150 ms B. 300 ms C. 50 ms D. 10 ms

Correct Answer is:A Most vendors recommend a unidirectional delay of 150 ms or less for VoIP communications.

When a controller-based WLAN is in use and roaming is desired with 802.1X/EAP, what solution may be used to implement fast and secure roaming? You must select 1 answer A. OKC B. DFS C. TPC D. WMM

Correct Answer is:A Opportunistic Key Caching (OKC) is a propular roaming methods that is not specified in the 802.11 standard. If an 802.11 standard method is desired, Fast BSS Transition (FT) should be used. DFS and TPC are used to accommodate radar detection and interference avoidance in some 5 GHz channels. WMM is a QoS certification by the Wi-Fi Alliance.

You are deploying an RTLS solution. What is an important requirement of most RTLS implementations? You must select 1 answer A. Sensors placed around the facility perimeter B. Use of at least one sensor for every STA C. Use of at least two sensors for every AP D. Implementation of VPN connectivity from the sensors to the monitoring server

Correct Answer is:A RTLS is incorporated into many WLAN vendor solutions today and it requires special design considerations. In many cases, the APs/sensors must be around the periphery of the area with additional APs/sensors throughout to accomplish proper triangulation processes. In most cases, a coverage-based WLAN design will not meet the requirements of RTLS.

What encryption algorithm is used by WPA2-Enterprise in secure WLANs using no deprecated 802.11 solutions? You must select 1 answer A. AES B. RC4 C. DES D. 3DES

Correct Answer is:A The Advanced Encryption Standard (AES) is used by WPA2-Enterprise and WPA2-Personal when implemented with non-deprecated 802.11 solutions. RC4 is used by WEP and TKIP and is deprecated for use with 802.11 devices. DES and 3DES have never been used or referenced within the 802.11 standard.

After performing corrective actions, according to the CWNP troubleshooting methodology, what action should be taken next? You must select 1 answer A. Verify the solution B. Document the results C. Discover the scale of the problem D. Define possible causes

Correct Answer is:A The CWNP methodology follows the sequence: Identify the problem, Discover the scale of the problem, Define possible causes, Narrow to the most likely cause, Create a plan of action or escalate the problem, Perform corrective actions, Verify the solution, Document the results.

When an 802.11 STA received a frame not intended for it, what field indicates the length of time required to complete the frame transaction after the current frame being received? You must select 1 answer A. Duration/ID B. Length C. Type D. Retry

Correct Answer is:A The Duration/ID field is used by non-target STAs to set their Network Allocation Vector (NAV) timer. The duration value is that required to complete the transaction after the current frame. For example, for a data frame, it includes the SIFS and Ack duration required to complete the transaction. The Length field is in the PHY PLCP header and not in the MAC header and it specifies the length of the current frame. The retry field is used to indicate whether the current frame is a first attempt or some retry attempt. The Type field is used to indicate whether the frame is a control, management, or data frame.

What organization defines the EAP protocol used in enterprise WLAN security? You must select 1 answer A. IETF B. IEEE C. FCC D. Wi-Fi Alliance

Correct Answer is:A The Extensible Authentication Protocol (EAP) is an IETF RFC-based standard. RFC 3748 defines the EAP standard.

What encryption solution is provided in the 802.11 standard and is not deprecated? You must select 1 answer A. AES B. RC4 C. RC5 D. SHA1

Correct Answer is:A The advanced encryption standard (AES) is the only non-deprecated encryption algorithm referenced in the 802.11-2016 standard and in current use in WLAN equipment.

What is the primary difference between throughput testing and load testing? You must select 1 answer A. Throughput testing is often a single machine test and load testing includes a simulated production load. B. Throughput testing provides no value while load testing does provide value. C. Throughput testing is not supported on WLANs, but load testing is. D. Load testing is not supported on WLANs, but throughput testing is.

Correct Answer is:A The biggest difference between throughput testing and load testing is that throughput testing is often based on a single machine communicating, while load testing can simulate multiple machines to be closer to real-world production performance levels.

What is a relative unit of measurement that allows comparison of the amplitude between two signals? You must select 1 answer A. dB B. RSSI C. dBm D. mW

Correct Answer is:A The decibel (dB) is a relative unit of measurement. For example, an antenna may add 6 dB of gain, but without knowing the input power (that to which the antenna gain is relative) you have no way to determine the actual power (absolute power) of the signal leaving the antenna. dBm and mW are absolute power metrics with dBm being logarithmic and mW being linear. RSSI is an arbitrary value defined in the 802.11 standard for received signal strength reporting.

What is used to synchronize the receiver for reception of an 802.11 PPDU? You must select 1 answer A. Preamble B. PLCP header C. MAC header D. FCS

Correct Answer is:A The preamble, which can include training fields, is used to synchronize the receiver for reception of the PPDU. The PPDU includes the PLCP header and the MPDU (MAC layer payload). The MPDU will have a MAC header and, possibly a data payload, and an FCS.

What kind of roaming may take place and include Layer 1 roaming? You must select 1 answer A. Band roaming from 2.4 GHz to 5 GHz B. Roaming from Wi-Fi to Ethernet C. Roaming from Wi-Fi to Token Ring D. No roaming involves Layer 1

Correct Answer is:A The primary roaming we consider at Layer 1 is that which occurs when a STA moves from a 2.4 GHz BSS to a 5 GHz BSS or vice versa. In this case, the client radio must switch from 2.4 GHz operation to 5 GHz operation.

You are using an 802.11 VoIP handset and walking around the facility frome end-to-end while on a call. What might you be testing in a newly deployed WLAN? You must select 1 answer A. Roaming capabilities B. Security capabilities C. Audio noise from RF energy D. Battery life of the VoIP handset

Correct Answer is:A This kind of testing is common to ensure proper VoIP operations while roaming. Testing with an active call is the most effective method of verification.

What metric ultimately determines the data rate that can be achieved between an AP and a STA? You must select 1 answer A. SNR B. Signal strength C. Noise floor D. Beacon rate

Correct Answer is:A To achieve a given data rate, a minimum Signal-to-Noise-Ratio (SNR) must be available. The signal strength alone is not sufficient, without consideration of the noise floor. The noise floor alone is not sufficient, without consideration of the signal strength. The SNR includes both.

What multi-antenna technology used at the transmitter to improve the signal received at the receiver was first introduced in 802.11n and standardized on a single option in 802.11ac? You must select 1 answer A. Transmit beamforming B. MRC C. STBC D. Diversity

Correct Answer is:A Transmit beamforming (also called TxBF) was introduced in the 802.11n standard, but narrowed to one method (explicit beamforming) in 802.11ac. It uses manipulated transmissions out of multiple antennas to cause signal upfade at the receiver for improved received signal strength.

What is the term used when measuring return loss caused by mismatched impedance in RF cables and connectors? You must select 1 answer A. VSWR B. EIRP C. IR D. Attenuation Factor

Correct Answer is:A Voltage Standing Wave Ratio (VSWR) is a measurement of the return loss in a system. When it is excessive, it can cause damage to equipment.

When using wireless design software for post-implementation validation, what is performed that is not performed in predictive modeling design scenarios? You must select 1 answer A. Capture of signals within the physical space B. Calibration or scaling of the floor plan C. Drawing walls and other materials D. Indicating AP locations

Correct Answer is:A When performing the validation survey, real signals will be captured in the physical space that houses the WLAN. This can also be done in full pre-deployment site surveys, but it is not performed when only performing a predictive modeling design.

You have implemented a real-time video conferencing system on your WLAN. What two factors will be most important to the quality of communications in this system? You must select 1 answer A. Throughput and reliability B. Latency and jitter C. Authentication and encryption D. Latency and encryption

Correct Answer is:A While all of the listed factors are important considerations, for a video conferencing, real-time system, throughput and reliability will be most important. Unlike VoIP, video conferencing systems are not impacted as much by jitter, though it is still a factor for the audio stream. Much higher levels of throughput are required than VoIP due to the existing video stream in the communications.

When an RF link in a bridging implementation spans more than 7 miles, what must be considered that need not typically be considered otherwise? You must select 1 answer A. Earth bulge B. FSPL C. SNR D. Output power

Correct Answer is:A You must always consider FSPL, SNR and output power in bridge links. When a link spans more than 7 miles, you must also consider earth bulge.

You are implementing an MDM solution. For what might this be used? You must select 1 answer A. High availability for controllers B. BYOD C. VPN endpoint D. Automatic channel selection

Correct Answer is:B A mobile device management (MDM) solution is used to manage mobile devices, which may include enterprise-owned devices as well as personal devices used through BYOD.

A push-to-talk device has similar requirements most alike to what other common WLAN client device? You must select 1 answer A. Laptop with standard data applications B. VoIP handset C. Handheld scanners D. 802.11 video cameras

Correct Answer is:B A push-to-talk device is most like a VoIP handset among those listed. Both use audio streaming protocols/codecs and require low latency and jitter.

You administer a WLAN that offers a guest SSID of CORPCUEST. Users connect to the CORPGUEST SSID, but report that they cannot access Internet web sites. The devices indicate no Internet connection. What common problem causes this scenario? You must select 1 answer A. NTP issues B. DNS failure C. Hardware issues D. IP routing issues

Correct Answer is:B An issue like this if commonly cause by DNS failures and captive portal failures. Given that multiple users are reporing the problem, it is not likely a hardware issue. If it were an IP routing issue, it would impact non-guest users as well.

A customer complains of low throughput when connected to the WLAN. When you evaluate the AP signal strength that covers his work location, you see that it is at -62 dBm. Fewer than 40 clients associate with the same AP. When you ask other users if they have experienced throughput problems, those farther from the original customer indicate that they do not and those closer to the original customer indicate that they do. All clients are on the 5 GHz AP channel. What is the likely problem among those listed? You must select 1 answer A. Improper use of band steering B. Non-Wi-Fi interference C. Low signal strength D. The use of a CAT5e cable for the AP connection

Correct Answer is:B Based on the description, the most likely problem is non-Wi-Fi interference in the local area where the complaining customer works. Other customers close to him also experience this interference and customers farther away, but connected to the same AP, do not.

What is a common solution to hidden node problems in WLANs? You must select 1 answer A. Reducing the client output power B. Enabling RTS/CTS C. Reducing the client antenna gain D. Increasing the AP fragmentation threshold

Correct Answer is:B By enabling RTS/CTS, you decrease hidden node problems. A very small RTS frame must get through to the AP in order to start the transaction (which includes RTS/SIFS/CTS/SIFS/DATA FRAME/SIFS/ACK).

What occurs naturally as an RF wave travels through space between antennas? You must select 1 answer A. VSWR B. FSPL C. Amplification D. Phase altering

Correct Answer is:B Free space path loss (FSPL) is the natural weaking of the RF signal amplitude as it travels through space and the wavefront spreads to cover an every larger area.

You have connected a controller-based AP to the LAN. The controller is located using DNS and you have verified that the proper host records are in DNS and that DHCP is properly configuring the AP. This is the only AP on the subnet in question. The AP cannot reach the controller, but it can reach other devices on the same subnet. It has an IP address of 192.168.12.37 based on the DHCP logs. What should you check among the listed items in an attempt to resolve the issue? You must select 1 answer A. Connect a laptop to the same Ethernet cable and verify DNS with NSLOOKUP B. Check the ACLs in the router connected to the subnet C. Connect a laptop to the same Ethernet cable and validate DHCP operations D. Make sure the Ethernet cable is plugged into the AP

Correct Answer is:B Given that local network communications are working and the DHCP log shows an IP settings assignment, it would be beneficial to check the access control lists (ACLs) in the router to make sure they are not preventing the AP from reaching the controller. The other suggestions listed are not relevant based on the description.

What high availability solution uses one controller as a backup for several other controllers in case a controller fails? You must select 1 answer A. RAID5 B. N+1 C. Striping D. Clustering

Correct Answer is:B N+1 allows multiple controllers (N) to have a single backup controller (1). The primary controllers operate as long as they are functional, but it one fails, the +1 controller takes over for that failed controller. This option is offered by several controller vendors.

You manage a WLAN with 200 802.11n APs and all APs are configured for 40 MHz channels in the 2.4 GHz and 5 GHz bands. The APs use band steering to encourage more clients to connect on the 5 GHz band. AirTime Fairness is also enabled and the low data rates of 1 and 2 Mbps are disabled. The 2.4 GHz clients are experiencing significant performance problems even though they connect to the various BSSs without problems. What should be changed in this configuration immediately to have the greatest impact on 2.4 GHz client performance? You must select 1 answer A. Enable the 1 and 2 Mbps data rates B. Change the 2.4 GHz channels to use only 20 MHz channel widths C. Turn off AirTime Fairness D. Turn off the 2.4 GHz radios on 75% of the APs

Correct Answer is:B Of the suggested actions, changing the channel widths from 40 MHz to 20 MHz in the 2.4 GHz band will improve the performance most. Using 40 MHz channels for all APs in 2.4 GHz results in excessive ACI and CCI, which significantly degrades performance. Turning off some 2.4 GHz radios would help (though not likely 75% of them), but it would not help as much as reducing the channel width. Given that all clients can connect with no problems, enabling the 1 and 2 Mbps data rates is also not likely to resolve the issue. Turning off AirTime Fairness will typically also have no impact in this scenario.

What is an important consideration when determining the impact of a non-Wi-Fi interferer on the 802.11 channels nearby? You must select 1 answer A. Protocols used by the interferer B. Frequencies used by the interferer C. Coding rate used by the interferer D. Age of the interfering device

Correct Answer is:B Of those listed, frequencies used by the interferer is the only important consideration. Additionally, air time utilization is a key measurement. These two facts related to the non-Wi-Fi interferer are most important in determining the degradation that will be caused by it.

When installing an omni-directional SISO antenna for outdoor coverage, what kind of mount is commonly used that includes u-brackets? You must select 1 answer A. Ceiling mount B. Pole/mast mount C. Wall mount D. Desktop mount

Correct Answer is:B Pole/mast mounts often use u-brackets to connect the antenna mounting kit to a pole or a mast.

When implementing a WLAN bridge link you must ensure 60% clearance of what defined zone? You must select 1 answer A. BSA zone B. Fresnel zone C. Antenna height zone D. PoE zone

Correct Answer is:B Remember that, for long distance links, you must keep the first Fresnel zone cleared by at least 60 percent and preferably 80 percent. This will ensure a consistent connection. You may have to plan for first Fresnal zone inspections periodically over the life of the link as foliage and new construction can interfere with the link over time.

Which one of these is not a good use of a spectrum analyzer? You must select 1 answer A. Locating sources of RF interference B. Determining retry rates on the WLAN C. Evaluating RF air time utilization in a channel D. Viewing historical RF activity in a channel

Correct Answer is:B Spectrum analyzers are mostly used for raw RF analysis. Therefore, locating interference, viewing channel RF utilization and historical RF activity are all practical applications. In most cases, a protocol analyzer is better for determining retry rates on the WLAN.

When an 800 nanosecond delay is inserted between symbols, what is certainly in use? You must select 1 answer A. DIFS B. Long guard interval C. SIFS D. Short guard interval

Correct Answer is:B The 802.11n amendment, now part of 802.11-2016, introduced the use of a short guard interval (SGI) that is 400 ns long. The original 800 ns guard interval is now the long GI. The guard interval is used between symbols and not between frames. Interframe spaces are used between frames.

What is typically mapped to the MAC address of the AP when only a single BSS is implemented by the AP? You must select 1 answer A. SSID B. BSSID C. ESSID D. DSM

Correct Answer is:B The BSSID is mapped to the AP MAC address in most situations when only a single BSS is implemented on the radio. When multiple BSSs (multiple SSIDs) are used, BSSIDs are generated for each SSID and look like MAC addresses.

What step comes after "Define the possible causes" when considering the CWNP troubleshooting methodology? You must select 1 answer A. Create a plan of action and implement it B. Narrow to the most likely cause C. Escalate the problem to the wireless vendor support staff D. Document the results and close the case

Correct Answer is:B The CWNP methodology follows the sequence: Identify the problem, Discover the scale of the problem, Define possible causes, Narrow to the most likely cause, Create a plan of action or escalate the problem, Perform corrective actions, Verify the solution, Document the results.

The documentation from your WLAN vendor indicates that the time clocks on all devices must be synchronized. What service may be used on the network to perform this action? You must select 1 answer A. DNS B. NTP C. RADIUS D. LDAP

Correct Answer is:B The Network Time Protocol (NTP) is used to synchronize the clocks on network devices. A time server can be configured, which acquires its time from an Internet time clock, and used to set the time for all internal devices. DNS is used for host name resolution. RADIUS is used for authentication. LDAP is used to access network directory services.

What is the basic process of Open System authentication? You must select 1 answer A. Authentication request, ID request, ID response, Authentication response, Association request, and Association response B. Authentication request, Authentication response, Association request, and Association response C. Authentication request, Association response D. Authentication request, Probe response, Association request, Probe response

Correct Answer is:B The basic process of Open System authenticaiton begins with an authentication request and authentication response. If the response is successful, the next step is an association request and association response. No ID is used in Open System authentication. It is simply a method to establish an active association between two 802.11 peers and through the process ensuring the ability to communicate.

A WLAN transmitter that emits a 20 mW signal is connected to a cable with 6 dB loss. If the cable is connected to an antenna with 12 dBi gain, what is the EIRP at the antenna element? You must select 1 answer A. 120 mW B. 80 mW C. 5 mW D. 320 mW

Correct Answer is:B The calculation can be completed with the cumulative nature of dB mat. -6 dB added to +12 dB is equal to +6 dB. Now, 20 mW +6 dB is equal to 80 mW (20 mW * 2 * 2).

An 802.11-based network includes two laptops, one mobile phone, and one tablet. No AP is involved in the communications. What WLAN use case is described? You must select 1 answer A. BSS B. IBSS C. ESS D. WWAN

Correct Answer is:B The described use cases is an ad-hoc network, defined in the 802.11 standard as an independent basic service set (IBSS). When an AP is used to build the BSS, it is an infrastructure BSS, but it simply uses the acronym BSS.

When a new PHY is to be created for the 802.11 standard, what is formed first? You must select 1 answer A. Draft B. Working group C. Ratified amendment D. Proposals

Correct Answer is:B The first thing that is formed is a working group. The working group will see the change through the draft and ratification phases until the amendment either becomes part of the standard or is dropped without ratification.

Why are some WLAN client devices able to receive signals at given data rates that are weaker than other client devices can receive? You must select 1 answer A. The device drivers are coded according to better programming practices. B. The receive sensitivity is better on some devices than others. C. The output power is higher on some devices than others. D. The VSWR is higher on devices that can receive weaker signals.

Correct Answer is:B The receive sensitivity varies from one device to another. When the receive sensitivity is improved, the device can receive weaker signals than can be received by devices with poorer receive sensitivity.

You are reporting on the RF environment in your facility. The manager asks you do describe the SNR noted in the report. Which of the following is the best explanation? You must select 1 answer A. SNR is the difference between the SOM and the Fade Margin B. SNR is the difference between the noise in the environment and the RF signal strength C. SNR is the simple noise reduction algorithm used on filters on 802.11 adapters D. SNR is the interference caused by USB 3.0 devices

Correct Answer is:B The signal-to-noise (SNR) ratio is not so much a ratio as simply the difference between the noise floor and the desired signal's strength. For example, if the noise floor is -94 dB and the signal is -53 dB, the SNR is 41 dB. The ability to properly interpret (demodulate) signals is directly related to the SNR. When SNR values are higher, more complex modulations may be used that result in higher data rates.

What will decrease in an environment when the noise floor increases? You must select 1 answer A. Signal strength B. SNR C. Transmit power D. Antenna gain

Correct Answer is:B The signal-to-noise ratio (SNR) will decrease when a higher noise floor is present. That is, if the signal strength is -70 dBm and the noise floor is -98 dBm, the SNR is 28 dB. If the noise floor increases to -93 dBm, the SNR will decrease to 23 dB.

When implementing PoE, what role is played by a wireless AP? You must select 1 answer A. PSE B. PD C. Midspan injector D. Power splitter

Correct Answer is:B The wireless AP will be a PoE client known as a powered device (PD) in the 802.3 standard. Power sourcing equipment (PSE) includes PoE capable switches and midspan injectors. A power splitter or PoE splitter is a newer device that allows you to split PoE power and Ethernet signals at the powered location so that a non-PoE device can be powered and have Ethernet connectivity, such as a wall power video camera with an Ethernet port.

A temporary mobile office is being deployed. In addition to the local WLAN, what will be required to provide Internet access at the site among the listed options? You must select 1 answer A. Ethernet switches and IP routers B. Wireless backhaul C. RADIUS server D. LDAP server

Correct Answer is:B To provide Internet access, some link, such as a wireless backhaul link, will be required for Internet connectivity. Typically, such temporary mobile sites do not deploy infrastructure gear such as Ethernet switchs and IP routers.

When an 802.11 amendment is ratified, what happens to the standard? You must select 1 answer A. The amendment specifications are optional and never become part of a rollup update. B. The standard includes the specifications of the amendment even though they are not included in a rollup update initially. C. Device manufacturers must wait until the next rollup to include the amendment specifications in chipsets and drivers. D. Amendments are created to resolve errors in the standard and introduce no new features.

Correct Answer is:B When an 802.11 amendment is ratified, it immediately becomes part of the standard. At some eventual point it will be included in a rollup of the standard, but its specifications are available immediately for implementation by device manufacturers if they desire.

An organization is planning to implement a new WLAN. They will install 20 APs and place them all on the same IP subnet so no IP roaming will be required for WLAN clients. The DHCP server will use the subnet of 192.168.10.0/24. They expect an average of 18 client STAs per AP. What is your immediate concern with this plan? You must select 1 answer A. APs cannot handle more than 15 STAs per AP B. The DHCP pool is not large enough C. IP roaming occurs even when all APs are on the same IP subnet D. WLANs must use the 10.x.x.x networks

Correct Answer is:B With a 24-bit subnet mask (255.255.255.0) only 256 addresses exist. The 0 address identifies the subnet and the 255 address is for broadcasts, leaving only 254 addresses. Each AP will use one IP address, for 234 remaining addresses. With 18 clients on each of 20 APs, the total client pool is 360. Clearly, the DHCP scope is insufficient for the need.

When using 802.1X/EAP authentication, what is the most common authentication server used in organizations? You must select 1 answer A. AD DS Domain Controller B. TACACS C. RADIUS D. Controller

Correct Answer is:C A RADIUS server is the most commonly implemented authentication server type in modern WLANs. TACACS or TACACS+ could be used with some architectures, but it is not the most common selection. AD DS Domain Controllers may provide credentials to the RADIUS server for authentication. A controller may be able to act as the authentication server, but in most cases, it does so by implementing RADIUS.

You are troubleshooting a performance problem experienced by several STAs in an area approximately five square meters in size. You want to see if a non-Wi-Fi interferer is in the space. What tool should you use? You must select 1 answer A. WLAN scanner B. WLAN protocol analyzer C. Spectrum analyzer D. Throughput tester

Correct Answer is:C A spectrum analyzer must be used to determine if a non-Wi-Fi interferer is in the area with certainty. A protocol analyzer may show retries, but the retries can be caused by other problems. A WLAN scanner will not help in this situation and neither will a throughput tester (with the possible exception of verifying that a device cannot achieve expected throughput in that area.

You have determined that an AP is not getting sufficient PoE power because it will not power up. You have verified that the CAT6 cable is only 30 meters in length and is connected to a switch port with PoE enabled. What should you check next? You must select 1 answer A. Verify that the CAT6 cable is blue and not yellow B. Verify that the midspan injector is powered on C. Verify that the power budget in the switch as sufficient remaining power for the AP D. Verify that the AP has the "use PoE" hardware switch set to "on"

Correct Answer is:C APs that use PoE do not have hardware switchces to enable it. PoE is automatically detected on the Ethernet cable. In this scenario, because the cable is not too long, you should verify the power budget is available in the switch. A midspan injector is used when a PoE switch is not available.

You must enable a feature on APs that allows for higher data rate clients to receive more time for frame reception from the APs than lower data rate clients. What is this feature? You must select 1 answer A. Load Balancing B. Band Steering C. AirTime Fairness D. RTS/CTS

Correct Answer is:C AirTime fairness is a downlink feature of some APs that allows higher data rate clients to receive more airtime for frame reception than lower data rate clients.

What is a primary benefit of EAP-TLS, EAP-TTLS, and PEAP that is not available in WEP and Shared Key Authentication? You must select 1 answer A. Encryption B. Authentication C. Dynamic encryption keys D. No certificate requirements

Correct Answer is:C All EAP types used in WLANs require at least a server certificate. Encryption and authentication are both provided by WEP and Shared Key authentication, though they are weak and should not be used. All EAP types used in WLANs provide dynamic encryption keys.

How can a transmitting client STA determine whether a data frame transmitted to the AP was delivered or not? You must select 1 answer A. If the AP transmits any other frames, the STA can assume it received the transmitted frame. B. If no collision was detected, the data frame was delivered. C. If a matching Ack frame is received, the data frame was delivered. D. Frames are always delivered on the WM, so the STA can assume delivery.

Correct Answer is:C Collisions cannot be detected on the wireless medium (WM), therefore, 802.11 networks use acknowledgement frames (Ack frames and Block Ack frames) to notify the transmitter of proper reception. If an Ack or Block Ack frame is received, the STA can trust that the frame was transmitted and received by the AP successfully.

What kind of WLAN management solution does not include centralized 802.11 MAC processing of any kind, but does include centralized configuration of the APs without the use of the Internet? You must select 1 answer A. Cloud-based B. Controller-based C. WNMS-based D. Virtual controller-based

Correct Answer is:C Controller- and virtual controller-based APs have some MAC operations in the controller. Cloud-based APs require access to the Internet. A WNMS may manage AP configuration and even monitor the AP, but not MAC operations take place in the WNMS solution.

In addition to capacity analysis results, what should be included in a site survey report to ensure WLAN users are provided with connectivity? You must select 1 answer A. Application Layer protocol availability analysis results B. Layer 4 protocol availability analysis results C. Coverage analysis results D. WAN interface analysis results

Correct Answer is:C Coverage is first; capacity is second. If you test capacity at a particular location, this does not ensure that the clients will have the needed coverage at another location. Coverage and capacity must be ensured.

What common building component is likely to cause coverage holes in a WLAN deployment if not considered and resolved in the WLAN design? You must select 1 answer A. Windows B. Cubicle partitions C. Elevators D. Tile floors

Correct Answer is:C Elevators, due to their shaft designs and the elevator construction materials, can cause dead spots when an AP is located on one side of the elevator and RF coverage is desired on the other side. The problem is often resolved by ensuring that APs are placed on both sides of the elevators on each floor.

What common feature of MDM solutions can be used to prevent users from causing data leaks by taking photos of sensitive documents? You must select 1 answer A. Self-registration B. Onboarding C. Feature management D. Over-the-air registration

Correct Answer is:C Feature management, in MDM solutions, often includes enabling/disabling the camera on smartphones and tablets. By disabling the camera, you can prevent data leakage through photos taken of sensitive documents.

What kind of 802.11 device is most likely to have multiple LAN switch ports, a WAN/Internet port, and dual-band 802.11 radios? You must select 1 answer A. Enterprise AP B. WLAN bridge C. Home WLAN router D. Mesh AP

Correct Answer is:C Home WLAN routers typically includes four or more LAN switch ports, an Internet or WAN port, and dual-band 802.11 radios. Enterprise APs will have dual-band radios and one or two Ethernet ports, but no Internet or WAN port (effectively a router interface). A WLAN bridge typically has the same interfaces as an Enterprise AP and a mesh AP does as well.

In an 802.11 2.4 GHz system, what 20 MHz channels are considered non-overlapping? You must select 1 answer A. 1 and 5 B. 3 and 6 C. 4 and 9 D. 2 and 5

Correct Answer is:C In the 2.4 GHz band, channel centers are 5 MHz apart. To be considered non-overlapping, they need 25 MHz of space between them. Therefore, the commonly used channels are 1, 6 and 11 as they are available in all regulatory domains. However, any two channels 25 MHz apart can be referenced as non-overlapping channels, such as 4 and 9.

When is an authentication response frame used? You must select 1 answer A. When an authentication request frame has been received B. When a client accidentally disconnects from the AP C. The 802.11 standard only specifies an authentication frame and not request and response frames for authentication D. When a probe request frame is received

Correct Answer is:C In the 802.11 standard, while there is an association request and association response frame used by 802.11 Open System authentication, there is only an authentication frame. Whether it is a request or response depends on the sequence in the frame exchange.

Why is it unlikely that an 802.11ac wave 2 AP with four spatial streams will exceed the capacity of a 1 Gbps Ethernet link? You must select 1 answer A. Because users just don't use Wi-Fi that much B. Because the AP will compress data sent onto the wired network C. Because 802.11 network operations consume significant air time and clients connect at varying data rates resulting in much lower useful data throughput than the maximum data rate of 802.11ac 4 stream APs D. Because the 1 Gbps Ethernet link can actually transmit 2 Gbps of data when the downlink and uplink wire pairs are both used for uplink transmission

Correct Answer is:C It is a common myth that 802.11ac wave 2 APs will all exceed the speeds of a 1 Gbps Ethernet link. The maximum data rate of an 802.11ac 4 stream channel running at 160 MHz is just under 3.5 Gbps. However, very few clients are 4 stream clients (many are 1 or two stream clients). Additionally, 160 MHz channels are not used today in enterprise deployments. Even if an 80 MHz channel is used, the average data rate for client STAs will be closer to 650 Mbps based on average spatial streams of 2 and varied signal strength at the receiver. Therefore, while some burst transmissions may experience slightly less performance (though this is debatable) because of the 1 Gbps Ethernet link, overall no significant performance degradation will be perceived. This may change in the future, but it is the most common reality today. The exception to this would be an unusual scenario where all client devices are 3 or 4 stream and have sufficient signal strength to use the highest modulation rates.

What feature of APs is often thought to be a security solution, but provides no real security because of simple spoofing methods? You must select 1 answer A. SSID hiding B. Shared Key Authentication C. MAC filtering D. WEP

Correct Answer is:C MAC filtinring provide no significant security because valid MAC addresses are seen in all data frame exchanges on the WLAN. An attacker need only spoof a valid MAC address to communicate on the network if MAC filtering is used alone.

What new transmission technology was introduced in 802.11ac that allows for an AP to transmit to more than one client STA concurrently? You must select 1 answer A. TxBF B. MIMO C. MU-MIMO D. MRC

Correct Answer is:C Multi-user MIMO was introduced in 802.11ac and supports downlink simultaneous transmissions to compatible clients in the right conditions. MIMO was introduced in 802.11n and works in both downlink and uplink communications.

What is an advantage of a centralized WLAN monitoring solution that is not available in most laptop-based protocol analyzers? You must select 1 answer A. Frame capture and decoding B. Expert views C. Data aggregation from multiple real-time sources for automated reporting and analysis D. Traffic statistics for the BSA

Correct Answer is:C Of those listed, data aggregation for multiple sources is the least common feature of laptop-based analyzers that is found in centralized monitoring solutions. The aggregated data can be used to proactively address future problems and troubleshoot existing issues on the WLAN.

What kind of MIMO antennas are typically used for WLAN deployments when the antennas are placed central to the target coverage area? You must select 1 answer A. Patch B. Grid C. Omni-directional D. Panel

Correct Answer is:C Omni-directional antennas radiate out in all directions around the antennas and are usually placed central to the coverage area. Patch and panel antennas are typically placed at the edge of the coverage area and do come in MIMO configurations. Grid antennas are typically SISO highly directional antennas.

You wish to administer an AP over the wired network using the CLI. What protocol should you use to prevent eavesdropping on the administrative tasks? You must select 1 answer A. Telnet B. HTTP C. SSH2 D. SNMPv3

Correct Answer is:C SSH2 is the secure shell and provides remote CLI to devices. It encrypts the communications for privacy (confidentiality). Telenet sends the communications in clear text and is not immune to simple eavesdropping. HTTP and SNMPv3 are not used for direct CLI access.

What is used to determine the number of slot times used in the formula to calculate an AIFS duration when EDCA is used? You must select 1 answer A. Data rate B. Frame duration C. AIFS number (AIFSN) D. The AIFS duration is fixed for each PHY

Correct Answer is:C The AIFS duration varies for each access category (AC) defined in EDCA. An AIFSN is assigned to the AC and is used in the algorithm that calculates the AIFS duration. The defaults are 9 (AC_BK), 6 (AC_BE), 3 (AC_VI), and 2 (AC_VO). The formula is AIFS = AIFSN * SlotTime +SIFS. Given that the AIFS always includes a SIFS plus the AIFSN multiplied by the slot time for the PHY, the AIFS will always be longer than the SIFS. For your reference, the slot times for the 802.11 PHYs are DSSS (20 ms), HR/DSSS (20 ms), OFDM (9 ms), ERP (20 ms [long] or 9 ms [short]), HT (same as OFDM in 5 GHz and ERP in 2.4 GHz) and VHT (9 ms).

What is the first step in the CWNP troubleshooting methodology? You must select 1 answer A. Document the results B. Verify the solution C. Identify the problem D. Define possible causes

Correct Answer is:C The CWNP methodology follows the sequence: Identify the problem, Discover the scale of the problem, Define possible causes, Narrow to the most likely cause, Create a plan of action or escalate the problem, Perform corrective actions, Verify the solution, Document the results.

What is defined as a system used to interconnect a set of BSSs and integrated LANs to create an ESS? You must select 1 answer A. WM B. DFS C. DS D. STA

Correct Answer is:C The Distribution System (DS) is the interconnecting system that allows for the creation of an ESS on a LAN or across LANs. The Wireless Medium (WM) is the term used in the standard for the RF channel. A station (STA) is a wireless access unit, either a client or an AP in most cases. Dynamic Frequency Selection (DFS) is used to ensure that the WLAN does not interfere with important radar systems. The differences between the DS, DSS, DSM and distribution service are sometimes confusing. The distribution service (no acronym as it would conflict with distribution system) is the service within a STA that allows for MAC communications within the distribution system. The distribution system service (DSS) allows for communications among devices on the WM, including between BSSs, and within a BSS. The distribution system medium (DSM) is the connection between the APs in the network, such as Ethernet or a mesh network.

What PHY operates in 2.4 GHz and is capable of a maximum of 11 Mbps? You must select 1 answer A. HT B. ERP C. HR/DSSS D. DSSS

Correct Answer is:C The High Rate/Direct Sequency Spread Spectrum (HR/DSSS) PHY supports 5.5 and 11 Mbps data rates. All listed PHYs operate in 2.4 GHz, but DSSS has a lower maximum data rate (2 Mbps) and ERP and HT have higher maximum data rates (54 Mbps and 600 Mbps respectively).

In addition to modulation, guard interval, channel width, and the number of spatial streams, what impacts the data rate according to the 802.11-2016 MCS tables? You must select 1 answer A. RSSI B. Signal strength C. Coding D. Noise floor

Correct Answer is:C The MCS tables in the standard do not consider signal strength, RSSI, or noise floor. In production systems, these are important factors when determining the data rate that can be used, but the MCS tables focus on modulation, coding, guard interval, channel width and the number of spatial streams.

What defines data rates for HT and VHT devices? You must select 1 answer A. They are fixed at 150, 180 and 240 Mbps B. They are fixed at 1, 2, 5.5 and 11 Mbps C. MCS tables D. PHY parameter tables

Correct Answer is:C The Modulation and Coding Scheme (MCS) tables define the data rates. Due to the complexity of data rate definition that was first introduces in HT (802.11n), MCS tables that map modulation, coding rates, number of spatial streams, channel width, and guard interval to data rates were created.

Which IEEE 802.11 Physical Layer (PHY) supports frequency use below 1 GHz and is optimal for low data rate long range communications? You must select 1 answer A. VHT B. HT C. S1G D. DMG

Correct Answer is:C The Sub-1 GHz (S1G) PHY operates below 1 GHz and is optimal for low data rate and longer range communications. VHT operates only in the 5 GHz band as a PHY. The HT PHY operates in either the 2.4 GHz or 5 GHz bands. The DMG PHY operates in the 60 GHz band and is intended for high data rate short range communications.

What new feature introduced with 802.11ac was designed to improve power management in the 5 GHz band? You must select 1 answer A. 8 stream MIMO B. 256-QAM C. VHT TXOP D. Consistent use of A-MPDU

Correct Answer is:C The VHT TXOP feature, which uses the partial AID in the PLCP header to determine if an incoming frame is for the listening STA, improves power management because the listening STA can sleep earlier in the frame transmission. Adding more streams increases power consumption. While 256-QAM may have a side benefit of reducing power consumption (due to shorter transmission times at higher data rates), it was not designed to improve power management. The standardized, full-time use of A-MPDU does not have a significant impact on power management either.

When implementing SSIDs in APs, to what are they typically mapped for better control of access to resources on the LAN? You must select 1 answer A. IP addresses B. MAC addresses C. VLANs D. User profiles

Correct Answer is:C The VLAN can be configured in relation to the SSID within the AP configuration profile. It can also be configured through information provided by the RADIUS server at the time of authentication. Additionally, VLANs can simply be assigned based on the switchport configuration to which the AP is connected. That is, with an autonomous or cloud-managed AP, the switchport can determine the VLAN on which all traffic coming from the AP is placed.

When centralized data forwarding is used in a controller-based architecture, what device creates the 802.3 Ethernet frames, removing all 802.11-specific information, and properly tags them with QoS markings to be forwarded onto the final destination? You must select 1 answer A. AP B. Client C. Controller D. IP router

Correct Answer is:C The controller receives the 802.11 frames in a tunnel from the AP and then removes all 802.11-specific information before creating and sending a QoS-tagged Ethernet frame.

What phrase defines an Intentional Radiator? You must select 1 answer A. The power output from the radio into the RF cable B. The power output from the antenna C. The power provided to the antenna including radio output power and all cable and connector losses D. The power received by the receiving antenna

Correct Answer is:C The intentional radiator, in a WLAN transmission system, is the point at which the antenna is connected. The signal originates at a transmitter and may pass through connectors, amplifiers, attenuators, and cables before reaching the antenna. These components amplify or attenuate the signal resulting in the output power at the intentional radiator before entering the antenna.

When using a protocol analyzer, what should you look at to see the duration value for a particular data frame in the capture? You must select 1 answer A. Expert views B. Traffic flows C. Packet decode D. Traffic statistics

Correct Answer is:C The packet decode must be used to view and evaluate specific field values, such as the Duration/ID field. The expert views show summary information useful for particular analysis situations. Traffic flows are used to view sequential exchanges in a communication. Traffic statistics provide metrics on the amount of traffic and type of traffic traversing the network.

You are passing random UDP data across the WLAN and measuring results with iPerf. What kind of test is most likely being performed? You must select 1 answer A. Interference location B. Signal strength monitoring C. Throughput test D. Black box testing

Correct Answer is:C This action describes a throughput test utility. iPerf is an open source throughput testing application.

You are implementing a VHT-capable AP. When operating in VHT mode, which one of the following channels is not available for use by the AP? You must select 1 answer A. 153 B. 144 C. 11 D. 56

Correct Answer is:C VHT operates only in the 5 GHz band, therefore, 2.4 GHz channels are not available to an AP or client when it is operating in VHT mode. 2.4 GHz channels include channels 1-14.

What is true about WPA in 802.11 wireless networks? You must select 1 answer A. WPA implements AES encryption in the same way that WEP does. B. WPA is based on CCMP/AES and is non-deprecated in the 802.11-2016 standard. C. When WPA is used, 802.11n and 802.11ac devices fall back to 54 Mbps as the highest data rate. D. WPA is based on TKIP/RC4 and is non-deprecated in the 802.11-2016 standard.

Correct Answer is:C WPA is based on TKIP/RC4 and is deprecated in the 802.11-2016 standard. When used, the standard requires that 802.11n and 802.11ac devices not use the HT or VHT PHY format and they must, therefore, fall back to 54 Mbps as the highest data rate (OFDM and ERP).

An AP that uses PoE powers up, but upon inspection you notice that only one radio (the 2.4 GHz radio) is active. You verify that the configuration has both the 2.4 GHz and 5 GHz radios enabled. When you connect the AP to wall power, both radios work as expected. What is a likely cause of this problem? You must select 1 answer A. The AP firmware is faulty B. The external antennas for the 5 GHz radio are not connected C. Insufficient PoE power D. WPA is enabled on the 5 Ghz radio, causing it to be disabled

Correct Answer is:C When an AP receives insufficient power, it may not power on or it may power on with limited features. For example, it may disable a radio chain or it may disable an entire radio. Always ensure the proper PoE power is provided to the AP from the swtich or midspan injector.

When is a three dimensional RF channel plan always required? You must select 1 answer A. When the WLAN is near an airport or military base B. When the WLAN exists in an industrial environment C. When a multi-floor WLAN is implemented D. When the Fresnel zone is 80% blocked

Correct Answer is:C When implementing a WLAN in a multi-floor deployment, a 3D channel plan must be used. RF signals will propagate above the ceiling and below the floor impacting floors above and below the current floor. This excess signal strength must be considered and accounted for in the channel plan.

When implementing a WLAN for corporate data access, you are planning for WPA2 implementation. What issue related to planning corporate data access are you considering? You must select 1 answer A. Ensure sufficient coverage B. Ensure sufficient throughput C. Ensure sufficient security D. Ensure availability

Correct Answer is:C You must consider authentication, authorization, confidentiality and integrity. Authentication can be provided with 802.1X. Authorization can be implemented using VLANs and role-based access control. Confidentiality can be provided with CCMP/AES encryption. Finally, integrity can be provided with integrity checks.

A AP transmits with an output power level of 25 mW and uses a 3 dBi antenna. What is the EIRP? You must select 1 answer A. 3 dBm B. 5 dBm C. 10 dBm D. 17 dBm

Correct Answer is:D 17 dBm is equal to 50 mW. 25 mW * 2 is 50 mW. When you add 3 dBi of antenna gain, you double the output power from the antenna, which is where EIRP is measured.

You have several 802.11n APs that require only 802.3af PoE power. What is the minimum power that is expected to be available for the PD in this scenario assuming proper cable lengths are used? You must select 1 answer A. 30 W B. 15.4 W C. 25.5 W D. 12.95 W

Correct Answer is:D 802.3af offers 12.95 watts of power at the PD, even though it can place up to 15.4 watts of power on the cable. Due to attenuation, the received power is less than the transmitted power. 802.3at offers 25.5 watts at the PD and places up to 30 watts onto the cable.

What solution can detect and mitigate rogue devices discovered on the WLAN? You must select 1 answer A. LDAP server B. RTLS server C. Host-based IDS D. WIPS

Correct Answer is:D A Wireless Intrusion Prevention System (WIPS) can be used to both detect and mitigate rogues on the WLAN. LDAP servers are servers that support the LDAP protocol for network directory access. RTLS servers are used with real-time location systems (RTLS) to locate devices on the network. Host-based IDS solutions are used on devices and are not used to detect and mitigate (contain) rogue devices.

What can a client device use to determine whether a BSS supports WMM QoS capabilities? You must select 1 answer A. Control frame analysis of existing associated STAs B. Data frame analysis of existing associated STAs C. QoS Query frames D. Beacon frame information

Correct Answer is:D A client can gather significant information from Beacon frames to determine if the transmitting AP is operating a desired BSS. This information includes security parameters, supported data rates, WMM QoS information, and more.

What is the output of a link budget? You must select 1 answer A. System Cost (SC) B. Signal-to-Noise-Ratio (SNR) C. Total Cost of Ownership (TCO) D. System Operating Margin (SOM)

Correct Answer is:D A link budget includes the transmit power, antenna gain, cable and connector losses, FSPL, and receiver sensitivity. The results of a link budget is an SOM.

An RF wave is weaker after traveling through some material in its path, what is the term used to describe what happened as the RF wave passed through the material? You must select 1 answer A. Reflection B. Refraction C. Scattering D. Absorption

Correct Answer is:D Absorption occurs when an RF wave travels through a material that converts the RF wave energy to heat as it passes through. Some of the RF wave energy is lost and some of it passes through the material. For example, a wall may absorb 4 dB of signal strength so that a signal entering the wall at -46 dBm exits the wall at -42 dBm even though only a few inches of distance are travelled.

Which one of the following is a kind of 802.11-based interference caused by 802.11 devices? You must select 1 answer A. RFID B. ZigBee C. Bluetooth D. ACI

Correct Answer is:D Adjacent Channel Interference (ACI) can be overlapping ACI or non-overlapping ACI. In either case, it is the results of operations on a different channel wherein the signal causes interferance with the interfered channel because of high output power or overlapping frequencies.

You have implemented a feature on the APs that temporarily ignores 2.4 GHz probe requests in order to direct more client STAs to 5 GHz channels. What is this feature? You must select 1 answer A. AirTime Fairness B. RRM C. Passpoint D. Band Steering

Correct Answer is:D Band steering can be an effective tool in all WLANs, but it is particularly beneficial in high density networks. It works by simply ignoring 2.4 GHz requests and responding to only 5 GHz requests once the 2.4 GHz maximum connection limit is reached. Alternatively, it will always delay a response in the 2.4 GHz band to see if the client attempts to connect on the 5 GHz band. If the client does not connect on the 5 GHz band, the AP may respond to future attempts (probe requests or authentication requests) in the 2.4 GHz band.

What statement about the beamwidth of an RF antenna is true? You must select 1 answer A. The horizontal and vertical beamwidth are measured where the main lobe loses 6 dB of power. B. Beamwidth has no impact on the propagation pattern. C. Horizontal beamwidth is displayed on the Elevation chart. D. As the gain of the antenna increases, the beamwidth decreases in either the horizontal or vertical direction or both.

Correct Answer is:D Beamwidth is measured at the points where the main lobe decreases in power by 3 dB. The horizontal beamwidth is typically shown on the Azimuth chart and the vertical beamwidth is shown on the Elevation chart. When the gain of an antenna increases, the beamwidth decreases. When the beamwidth increases, the gain decreases.

What statement is true about the Ethernet cables used for AP connectivity? You must select 1 answer A. If you use CAT6 cabling, you can install 250 metter cable runs instead of the 100 meter limit of CAT5e. B. PoE can operate across CAT5e cables, but CAT3 cables are sufficient for providing 802.3at PoE power. C. The minimum required Ethernet cable type for 802.11ac APs is CAT3. D. CAT6 Ethernet cables provide superior performance to CAT5 Ethernet cables.

Correct Answer is:D CAT6 cables still constrain the length to 100 meters; however, they provide superior performance than lower categories of cable. All PoE should run across CAT5 at a minimum.

What original authentication method of the 802.11-1997 standard is still included in the standard and non-deprecated? You must select 1 answer A. CCMP B. WEP C. Shared Key Authentication D. Open System Authentication

Correct Answer is:D CCMP was not in the original standard. WEP and Shared Key Authentication were in the original standard, but they are both deprecated. Only Open System Authentication, from the original standard, is non-deprecated and still in use today.

What 2.4 GHz channels are available worldwide in all regulatory domains? You must select 1 answer A. 1 through 14 B. 1 through 13 C. 1 through 12 D. 1 through 11

Correct Answer is:D Channels 1 through 11 are available in all regulatory domains worldwide. For this reason, some client devices only support these channels. Some regulatory domains allow for channels 12 and 13 as well. Japan allows limited use of channel 14.

If the center frequency of channel 2 is 2417 MHz, what is the center frequency of channel 5? You must select 1 answer A. 2485 B. 2412 C. 2420 D. 2432

Correct Answer is:D Given that the channels are 5 MHz apart in 2.4 GHz, simply add 15 MHz to the known center frequency of channel 2 and you arrive at 2.432 GHz or 2432 MHz for channel 5.

You are troubleshooting a problem with a USB adapter on a laptop. When you insert the adapter, after having installed the drivers, it is not detected by the operating system and no wireless networks are shown. The adapter has been tested on another machine where it works properly. What is a practical next action to take in this scenario? You must select 1 answer A. Reinstall the operating system on the problem laptop B. Delete the driver from the problem laptop and use the adapter without a driver C. Install a third-party supplicant to use the adapter in the problem laptop D. Check the driver version in use on the working computer and ensure the same driver version is used on the problem laptop

Correct Answer is:D In cases like this, the driver can be the problem. If the version used on the problem laptop is different from that used on the working laptop, you should install the working version to see if it resolves the problem. Faulty drivers can cause problems ranging from not detecting the adapter to the adapter working, but only in one band even through it is a dual-band adapter.

What Wi-Fi Alliance certification/standard can be used by hotspots to allow client devices to connect automatically if the hotspot supports a subscription service to which the client is subscribed? You must select 1 answer A. Voice-Enterprise B. WMM C. WPA2 D. Passpoint

Correct Answer is:D Passpoint certification and Hotspot 2.0 are Wi-Fi Alliance certifications and standards respectively that allow for this functionality. Voice-Enterprise is a certification that validates VoIP operations across 802.11 networks that involve multiple APs. WMM is a QoS-related certification and WPA2 is a security certification.

What feature of WLAN APs may provide for automatic negotiation of AP channel and power settings among the APs or within the controllers? You must select 1 answer A. Band Steering B. AirTime Fairness C. Load balancing D. RRM

Correct Answer is:D Radio Resource Management (RRM) or ARM in Aruba Networks APs, can automatically configure the channel and output power settings for APs and it includes extra deatures such as coverage hole detection (dead spot detection) and mitigation.

What configuration option is sometimes thought to be a security solution for WLANs, but is easily circumvented by attackers? You must select 1 answer A. CCMP B. WPA2 C. EAP-TLS D. SSID hiding

Correct Answer is:D SSID hiding is a weak option from a security perspective. The SSID can be easily located with tools available for download from the Internet and the SSID is in frames other than the Beacon frame. It should not be relied upon for any level of security.

When an RF wave encounters obstacles smaller than the wavelength and reflective in nature, what is likely to occur? You must select 1 answer A. Warping B. Reflection C. Refraction D. Scattering

Correct Answer is:D Scattering occurs when the RF wave encounters small obtacles (in relation to the wavelength) that are reflective in character. Reflection occurs when the RF wave encounters obstacles larger than the wavelength. Refraction occurs as the RF wave passes through a medium and bends as it traverses through it.

What statement is true regarding the use of the ERP PHY in 802.11 networks? You must select 1 answer A. ERP operates in either 2.4 GHz or 5 GHz and supports a maximum data rate of 54 Mbps. B. ERP is identical to OFDM PHY, except it operates in the 5 GHz band whereas OFDM operates in the 2.4 GHz band. C. ERP uses 256-QAM modulation to achieve the maximum data rate of 54 Mbps. D. ERP operates only in the 2.4 GHz band and supports a maximum data rate of 54 Mbps.

Correct Answer is:D The Extended Rate PHY (ERP) operates in the 2.4 GHz band with no 5 GHz band support. It implements OFDM modulation that was first used in the OFDM PHY. The maximum data rate of the ERP PHY is 54 Mbps in the standard.

What term describes an RF transmission system up to but not including the antenna? You must select 1 answer A. Chipset B. Radio C. EIRP D. Intentional Radiator

Correct Answer is:D The Intentional Radiator (IR) includes everything in the transmission system except the antenna. The power output of the IR would be measured at the point where it enters the antenna element.

What organization certifies equipment to interoperate with other 802.11-based equipment? You must select 1 answer A. IEEE B. IETF C. FCC D. Wi-Fi Alliance

Correct Answer is:D The Wi-Fi Alliance grants certifications to tested equipment validating interoperability and performance related to security, QoS, power management, VoIP and connectivity.

What is in HT and VHT PHY preambles that allows for the synchronization of the receiving radio? You must select 1 answer A. Length field B. Data rate specification C. Duration field D. Training fields

Correct Answer is:D The training fields are used in HT and VHT (as well as OFDM and ERP) PHYs to synchronize the receiver with the incoming signal. The length field in the PHY PLCP header indicates the length (in octets or bytes) of the current frame. The data rate indicates the rate at which the PSDU (or MPDU if you prefer) will be transmitted. The Duration (or Duration/ID) field is in the MAC header and not the PHY preamble or PHY PLCP header.

What is required before a Block Acknowledgement can be used? You must select 1 answer A. 802.11g must be the active PHY B. 802.11i must be implemented in the BSS C. A sounding exchange must take place D. A block acknowledgement request exchange must take place

Correct Answer is:D To use Block Ack frames and acknowledge a block of frames (multiple frames) in one acknowledgement, a block acknowledgement request exchange must first take place between two peers. This exchange establishes the allowed duration of the block of frames and begins the process of a block ack implementation.

In what band do many USB 3 devices cause significant localized (within 3-5 meters) RF interference? You must select 1 answer A. 60 Ghz B. Sub-1 GHz C. 5 GHz D. 2.4 GHz

Correct Answer is:D USB 3.0 devices can create significant RF interference in the 2.4 GHz band. In fact, the USB 3.0 circuitry n the 802.11ac USB 3.0 adapter can raise the noise floor by 5-20 dB, reducing the higher data rates to all but impossible.

A manager has asked you to place the APs above the ceiling in a WLAN deployment. He has requested this for aesthetic reasons. You know this is not the best decision, what do you tell the manager in an attempt to influence him to make a better decisions? You must select 1 answer A. It is impossible to power APs placed above the ceiling. B. It is always against regulations to place APs above the ceiling. C. Placing the APs above the cealing will prevent any possible configuration that would allow for client access. D. Placing the APs above the ceiling will alter the requirements for the WLAN and may require more APs than would be otherwise needed.

Correct Answer is:D While it is possible to place APs above the ceiling, as long as it does not result in regulation non-compliance, it will significantly impact the coverage and capacity plan. The APs may have to use higher output power settings and more APs may be required. Additionally, CCI between APs within the ceiling (if the area is open) may be higher due to the installation of more APs or higher output power settings.