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Question 61.

Which value represents the background RF energy level measured by a receiver when no desired Wi-Fi transmission is being decoded?

1. Noise floor
   2. EIRP
   3. Antenna gain
   4. BSSID

Correct Answer: 1. Noise floor

Explanation:

The noise floor represents the ambient RF energy present in a frequency range as perceived by a receiver. It can include thermal noise, interference from electronic devices, and energy generated by other radio systems. The noise floor matters because a desired Wi-Fi signal must be sufficiently stronger than that background energy for reliable decoding. This relationship is expressed as signal-to-noise ratio, or SNR. EIRP describes effective transmitted power, antenna gain describes directional concentration of RF energy, and a BSSID identifies a Basic Service Set. A rising noise floor can reduce usable SNR even when RSSI appears unchanged, so WLAN troubleshooting should consider both signal strength and background noise.

Question 62.

A client receives a signal at -65 dBm while the noise floor is -90 dBm. What is the approximate SNR?

1. 15 dB
   2. 25 dB
   3. 65 dB
   4. 90 dB

Correct Answer: 2. 25 dB

Explanation:

SNR is calculated by comparing the received signal strength with the noise floor. With a signal of -65 dBm and a noise floor of -90 dBm, the difference is 25 dB. The result is expressed in dB because it represents a relative difference rather than an absolute power measurement. Higher SNR generally allows more complex modulation and coding schemes to operate reliably, while low SNR can cause retries, reduced PHY rates, and unstable connectivity. This example also demonstrates why RSSI alone is insufficient. A -65 dBm signal may be excellent in a quiet environment but much less useful if the noise floor rises close to the signal level.

Question 63.

Which RF characteristic describes the orientation of the electric field of an electromagnetic wave and should generally be aligned between transmitting and receiving antennas for best results?

1. Gain
   2. Frequency
   3. Polarization
   4. Reflection

Correct Answer: 3. Polarization

Explanation:

Polarization describes the orientation of the electric field of an electromagnetic wave. Common antenna polarizations include vertical and horizontal, though more complex forms also exist. For best coupling, transmitting and receiving antennas should generally have compatible polarization. Significant polarization mismatch can cause signal loss even when antennas are otherwise close and unobstructed. Gain describes the directional concentration of RF energy, frequency identifies the rate of electromagnetic oscillation, and reflection is a propagation behavior. WLAN designers should pay attention to antenna orientation because incorrectly mounted external antennas can introduce unnecessary loss and produce coverage patterns that differ substantially from the intended design.

Question 64.

Which antenna type is typically most appropriate for a point-to-point outdoor bridge where RF energy should be concentrated toward a distant site?

1. Omnidirectional ceiling antenna
   2. Low-gain dipole only
   3. Internal laptop antenna
   4. Highly directional antenna

Correct Answer: 4. Highly directional antenna

Explanation:

A highly directional antenna is generally appropriate for point-to-point links because it concentrates RF energy toward the intended remote location. Examples include dish, panel, and other directional antenna designs. Concentrating energy can improve link budget and reduce unnecessary RF energy in directions where it is not needed. Omnidirectional antennas provide broad horizontal coverage and are more appropriate for serving clients distributed around an access point. Internal laptop antennas are designed for client devices rather than infrastructure bridging. Directional links still require proper alignment, regulatory compliance, Fresnel zone considerations, mounting stability, weather protection, and accurate link-budget calculations.

Question 65.

Which term describes the area around the direct line-of-sight path between two antennas that should remain reasonably clear to support a reliable outdoor RF link?

1. Fresnel zone
   2. BSS boundary
   3. Contention window
   4. Beacon interval

Correct Answer: 1. Fresnel zone

Explanation:

The Fresnel zone is an elliptical region surrounding the direct line-of-sight path between transmitting and receiving antennas. Obstacles intruding into this region can cause diffraction and signal cancellation even when visual line of sight appears unobstructed. For reliable outdoor point-to-point links, designers generally seek adequate Fresnel zone clearance in addition to direct line of sight. The BSS boundary relates to WLAN cell coverage, the contention window is used in medium access procedures, and the beacon interval determines how often beacons are transmitted. Outdoor WLAN design should therefore consider terrain, trees, buildings, antenna height, earth curvature on long links, and Fresnel clearance rather than relying only on whether the antennas can visually see each other.

Question 66.

Which statement best describes free-space path loss?

1. Signal strength increases as distance increases
   2. RF energy spreads over a larger area as distance increases, reducing received power density
   3. It occurs only when walls are present
   4. It is caused only by encryption overhead

Correct Answer: 2. RF energy spreads over a larger area as distance increases, reducing received power density

Explanation:

Free-space path loss describes the reduction in received signal strength that occurs as RF energy propagates away from a transmitter and spreads over a progressively larger area. This loss occurs even in an ideal environment with no walls, interference, or obstacles. Physical materials can introduce additional attenuation beyond free-space loss, but they are not required for path loss to occur. Encryption has no relationship to free-space propagation. Understanding path loss is essential for link-budget calculations, AP placement, outdoor bridge design, and interpreting why a client farther from an access point generally receives a weaker signal than a client located nearby.

Question 67.

Which 802.11 frame subtype is used by a client to request permission to join an access point’s BSS after required preliminary procedures?

1. ACK
   2. Beacon
   3. Association Request
   4. CTS

Correct Answer: 3. Association Request

Explanation:

An Association Request is a management frame transmitted by a client when it wants to establish membership in an infrastructure BSS. The access point replies with an Association Response indicating whether the request was accepted. Beacon frames advertise WLAN information, while ACK and CTS are control frames. Association is an important stage of the WLAN connection process because it creates the logical relationship between the station and access point. When troubleshooting connection failures, analyzing Authentication, Association Request, and Association Response frames can reveal whether a client is failing because of unsupported capabilities, security configuration, access policies, or other association-related conditions.

Question 68.

Which 802.11 management frame can be used to terminate an existing association while not necessarily representing the same function as deauthentication?

1. Probe Request
   2. Beacon
   3. Authentication
   4. Disassociation

Correct Answer: 4. Disassociation

Explanation:

A Disassociation frame terminates the association relationship between a client and an access point. Deauthentication is a different management action that terminates authentication state. Although the two are often observed together during disconnect events, they represent different logical relationships in 802.11. Probe Requests support active scanning, Beacons advertise BSS information, and Authentication frames participate in authentication procedures. Understanding the difference between disassociation and deauthentication is useful when examining packet captures because the reason codes and frame sequence can provide clues about whether a client left intentionally, was removed by the infrastructure, experienced a policy event, or encountered connectivity problems.

Question 69.

Which control mechanism can help address hidden-node conditions by reserving the wireless medium before a data transmission?

1. RTS/CTS
   2. DHCP
   3. ARP
   4. DNS

Correct Answer: 1. RTS/CTS

Explanation:

Request to Send/Clear to Send, or RTS/CTS, is an 802.11 control mechanism that can help reduce collisions caused by hidden nodes. A transmitting station sends an RTS, and the receiving station responds with a CTS. Other stations that hear the CTS can update their virtual carrier-sense information and defer transmission for the indicated duration. DHCP, ARP, and DNS operate at higher layers and do not reserve the wireless medium. RTS/CTS introduces additional overhead, so it is not always beneficial to use it aggressively. However, it can improve reliability in environments where stations cannot hear one another but can both interfere with the same receiver.

Question 70.

Which field in 802.11 frames contributes to virtual carrier sensing by indicating how long the wireless medium is expected to remain reserved?

1. SSID field
   2. Duration/ID field
   3. IP TTL field
   4. TCP window field

Correct Answer: 2. Duration/ID field

Explanation:

The Duration/ID field in many 802.11 frames helps support virtual carrier sensing by indicating the amount of time required to complete a frame exchange. Other stations that receive the frame can use this information to update their Network Allocation Vector, or NAV, and defer transmissions until the reserved period expires. The SSID identifies a WLAN name, while IP TTL and TCP window fields belong to higher-layer protocols. Virtual carrier sensing complements physical carrier sensing, allowing stations to make better medium-access decisions even when they cannot hear every individual transmission in the exchange.

Question 71.

What is the purpose of the Network Allocation Vector in 802.11?

1. It stores a client’s IP address
   2. It records antenna gain
   3. It tracks the period for which the medium is virtually considered busy
   4. It selects the SSID

Correct Answer: 3. It tracks the period for which the medium is virtually considered busy

Explanation:

The Network Allocation Vector, or NAV, is used for virtual carrier sensing. When a station receives an 802.11 frame containing a duration value, it can update its NAV to indicate how long the medium is expected to remain reserved. During this interval, the station generally refrains from initiating a competing transmission. The NAV does not store IP addresses, antenna information, or SSID selection data. Virtual carrier sensing works alongside physical carrier sensing as part of the 802.11 collision-avoidance process. Understanding the NAV is particularly useful when analyzing RTS/CTS exchanges and the timing behavior of wireless frame sequences.

Question 72.

Which 802.11 concept defines specific waiting periods between frame transmissions and gives some frame types priority over others?

1. VLAN tagging
   2. DHCP relay
   3. Channel bonding
   4. Interframe spaces

Correct Answer: 4. Interframe spaces

Explanation:

Interframe spaces are defined waiting periods used between 802.11 transmissions. Different interframe spaces help establish transmission priority and coordinate access to the shared wireless medium. For example, an acknowledgment can be transmitted after a shorter waiting interval than a new contending data transmission, allowing the current frame exchange to complete efficiently. VLAN tagging, DHCP relay, and channel bonding solve unrelated networking problems. Interframe timing is fundamental to 802.11 medium access because Wi-Fi devices cannot simply transmit whenever they have data. They must follow timing and contention rules designed to reduce collisions and provide orderly access to the channel.

Question 73.

Which WLAN security standard introduced stronger protection based on AES and became the basis for Robust Security Network operation?

1. IEEE 802.11i
   2. IEEE 802.11b
   3. IEEE 802.11d
   4. IEEE 802.11h

Correct Answer: 1. IEEE 802.11i

Explanation:

IEEE 802.11i introduced major security enhancements for WLANs, including the Robust Security Network framework and stronger cryptographic protection using AES-based CCMP. WPA2 was closely associated with these improvements. Earlier mechanisms such as WEP were found to have serious weaknesses and are no longer considered adequate. 802.11b defines an older PHY technology, 802.11d addresses regulatory information, and 802.11h introduced spectrum-management mechanisms. CWNA candidates should understand the evolution from WEP to WPA/WPA2 and onward to stronger modern protections because security requirements affect authentication, encryption, management-frame protection, client compatibility, and overall WLAN design.

Question 74.

In an 802.1X enterprise WLAN, which device typically acts as the authenticator?

1. DNS server
   2. Access point or WLAN infrastructure device
   3. DHCP client
   4. File server

Correct Answer: 2. Access point or WLAN infrastructure device

Explanation:

In an 802.1X authentication architecture, the client is the supplicant, the access point or WLAN infrastructure acts as the authenticator, and an authentication server such as RADIUS validates credentials using an EAP method. The authenticator controls network access and relays authentication information between the supplicant and authentication server. DNS and file servers do not perform this role, while DHCP normally operates after sufficient network access has been established. Understanding these three roles is important for troubleshooting enterprise Wi-Fi because authentication failures may originate from the client configuration, WLAN infrastructure, RADIUS connectivity, certificates, identity stores, or EAP-method configuration.

Question 75.

Which protocol is commonly used between an 802.1X authenticator and a centralized authentication server?

1. RADIUS
   2. ARP
   3. ICMP
   4. FTP

Correct Answer: 1. RADIUS

Explanation:

RADIUS is commonly used between the authenticator and centralized authentication server in enterprise WLAN deployments. The access point or WLAN controller can encapsulate authentication information and communicate with the RADIUS server, which validates credentials or certificates according to the configured EAP method and identity infrastructure. ARP resolves IP-to-MAC mappings, ICMP supports control and diagnostic messaging, and FTP transfers files. Enterprise authentication provides advantages such as individualized credentials, centralized access control, policy enforcement, and improved accountability compared with a single shared password. Troubleshooting often requires examining WLAN logs together with RADIUS logs to determine where authentication failed.

Question 76.

Which WLAN security approach is generally more appropriate for a large enterprise that requires individual user authentication and centralized policy control?

1. Open network with no authentication
   2. Static WEP
   3. Shared password for every employee
   4. 802.1X with an appropriate EAP method**

Correct Answer: 4. 802.1X with an appropriate EAP method

Explanation:

802.1X with an appropriate EAP method is generally the preferred approach for enterprise WLANs that need individualized authentication and centralized policy control. It can integrate with authentication servers and identity systems, allowing organizations to manage users or devices without distributing one shared password to everyone. Static WEP is obsolete and insecure, while open networks provide no meaningful access authentication. Shared passwords can be practical in smaller or specialized environments but are harder to revoke selectively and provide less accountability. Enterprise deployments must also plan certificate trust, RADIUS availability, identity integration, and client configuration to ensure authentication remains both secure and reliable.

Question 77.

Which security feature protects selected 802.11 management frames against spoofing or tampering?

1. Protected Management Frames
   2. DHCP snooping
   3. Port mirroring
   4. NAT

Correct Answer: 1. Protected Management Frames

Explanation:

Protected Management Frames, commonly associated with 802.11w functionality incorporated into later 802.11 revisions, protect selected management frames from forgery and tampering. This helps reduce certain attacks involving spoofed deauthentication or disassociation frames. DHCP snooping protects DHCP operations on wired switching infrastructure, port mirroring supports traffic analysis, and NAT translates IP addresses. Management-frame protection does not encrypt every management frame or eliminate every wireless attack, but it strengthens WLAN security by protecting important robust management exchanges. Modern security designs increasingly rely on PMF, especially with newer Wi-Fi security standards.

Question 78.

Which survey type is performed before WLAN installation by using software models of the building and predicted RF behavior?

1. Post-deployment validation survey
   2. Predictive survey
   3. Spectrum-only troubleshooting survey
   4. Protocol capture survey

Correct Answer: 2. Predictive survey

Explanation:

A predictive survey uses building plans, modeled wall attenuation, access point specifications, antenna patterns, and other design inputs to estimate coverage and performance before hardware is installed. It is an efficient way to create an initial WLAN design, especially for large facilities. However, predictive results are based on assumptions and should normally be validated after deployment because actual construction materials, interference, furniture, users, and installation conditions can differ from the model. A post-deployment validation survey measures the installed network, while spectrum and protocol analysis are troubleshooting or diagnostic techniques rather than complete predictive design methods.

Question 79.

Which survey technique uses a temporary access point placed at proposed locations to collect actual RF measurements before final installation?

1. Passive-only documentation
   2. Predictive modeling only
   3. AP-on-a-stick survey
   4. Logical topology review

Correct Answer: 3. AP-on-a-stick survey

Explanation:

An AP-on-a-stick survey uses a temporary access point mounted at or near a proposed installation location so actual RF measurements can be collected before permanent deployment. This technique can provide valuable information about propagation, attenuation, antenna behavior, and coverage in environments where predictive modeling alone may be insufficient. It requires careful attention to the planned AP model, antenna type, mounting height, transmit power, and orientation so results represent the final installation accurately. Predictive models remain useful, but AP-on-a-stick measurements can improve confidence in challenging spaces such as warehouses, hospitals, manufacturing sites, or buildings with unusual construction materials.

Question 80.

Which approach is best when users report intermittent Wi-Fi failures only in one conference room even though neighboring areas work normally?

1. Replace every access point in the building immediately
   2. Assume DHCP is always the cause
   3. Increase every AP to maximum transmit power
   4. Collect localized RF, spectrum, protocol, and client measurements in the affected room to isolate the cause**

Correct Answer: 4. Collect localized RF, spectrum, protocol, and client measurements in the affected room to isolate the cause

Explanation:

A problem isolated to one physical area should be investigated with localized evidence. Useful measurements include RSSI, SNR, channel utilization, retry rates, spectrum activity, protocol captures, client capabilities, roaming behavior, and interference sources. A conference room may contain dense client populations, wireless presentation systems, Bluetooth devices, neighboring AP overlap, or other conditions not present elsewhere. Replacing all APs or increasing transmit power without diagnosis can introduce new problems, while assuming DHCP is responsible ignores the RF layer. A structured troubleshooting process should first reproduce the issue, gather data near the affected users, identify the failing layer, and then apply the smallest corrective change supported by evidence.