CWDP-305 Questions and Answers

Conducting a site survey in environments such as heavy machinery repair facilities involves potential hazards, including moving equipment, loud noises, and other safety risks.Therefore, wearing Personal Protective Equipment (PPE) is essential to ensure the safety of the surveyor.

The CWDP-305 Official Study and Reference Guide advises:

"When performing site surveys in industrial or hazardous environments, always adhere to safety protocols, including the use of appropriate Personal Protective Equipment (PPE) such as hard hats, safety glasses, and steel-toed boots."

This ensures that the survey is conducted safely and complies with occupational health and safety regulations.

Comprehensive and Detailed Explanation:

Return loss measures how well devices or lines match impedance, with higher values indicating better matching and less signal reflection. When measuring return loss through a cable with known loss, the actual return loss of the antenna is calculated by subtracting twice the cable loss from the measured value:

Measured return loss = 20 dB

Cable loss = 2.5 dB

Actual return loss = 20 dB - (2 × 2.5 dB) = 15 dB

However, since the question states the measured value is "larger than 20 dB," let's assume it's, for example, 22.5 dB:

Actual return loss = 22.5 dB - (2 × 2.5 dB) = 17.5 dB

An actual return loss of17.5 dBis considered acceptable and indicates a reasonably good impedance match, minimizing signal reflections.

Comprehensive and Detailed Explanation:

In the context of WLAN design, certain enterprise verticals have distinct requirements and considerations:

A. Education:Educational institutions often require robust WLANs to support high-density environments, BYOD policies, and seamless roaming across campuses.

C. Healthcare:Healthcare facilities demand WLANs that support critical applications, real-time data access, and stringent security protocols to protect sensitive patient information.

E. Retail:Retail environments utilize WLANs for point-of-sale systems, inventory management, and customer engagement through Wi-Fi services.

B. WarehousesandD. Office environmentsare also important but are not typically categorized among the top three enterprise verticals in WLAN design considerations.

Comprehensive and Detailed Explanation:

When discrepancies are found between the physical environment and the CAD drawings during a site survey, it's crucial to update the documentation to reflect the current state accurately. Redrawing the portions of the map that have changed ensures that the design and subsequent deployment are based on accurate information, leading to a more reliable and efficient wireless network.

Comprehensive and Detailed Explanation:

Locating 802.11 clients without dedicated tags relies on the clients actively transmitting signals.If a client's radio is disabled or the device is powered off, it will not emit any signals, making it impossible for the WLAN infrastructure to detect or locate it.While 802.11k support and RF channel selection can affect the accuracy and efficiency of location tracking, they do not prevent the basic ability to detect a client that is actively transmitting.

In this scenario, lightweight APs are connected to access ports on VLANs 7, 8, and 9. When these APs boot up, they obtain IP addresses via DHCP on the VLAN to which they are physically connected. Each AP then establishes a Layer 3 CAPWAP tunnel to the WLAN controller. The initial DHCP process occurs before the tunnel is established, so the IP address assigned to each AP is associated with its local VLAN (7, 8, or 9).DumpsPedia

Upgrading access points (APs) from 802.11n to 802.11ac can offer higher throughput and improved performance. However, to realize these benefits, client devices must also support the newer standard. If the clients remain on 802.11n, they cannot leverage the advanced features of 802.11ac, such as wider channel bandwidths, higher modulation schemes, and increased spatial streams.

The CWDP-305 Official Study and Reference Guide emphasizes the importance of considering client capabilities during WLAN upgrades:

"When upgrading a WLAN, it's essential to assess both infrastructure and client devices. Upgrading APs without corresponding client support may not yield the expected performance improvements."

Therefore, in this scenario, the most likely cause of the unchanged throughput is that the client devices were not upgraded to support 802.11ac.

The control plane in WLAN architectures is responsible for managing and optimizing various network functions to ensure efficient and reliable wireless communication. Key functions include:

Channel Reuse Plans:Determining optimal channel assignments to minimize interference and maximize spectrum efficiency.

Mobility Management:Facilitating seamless client roaming between access points without service interruption.

Transmit Power:Adjusting the power levels of access points to ensure adequate coverage while reducing interference.

Load Balancing:Distributing client connections across multiple access points to prevent overloading and maintain performance.

These functions are critical in both centralized and distributed WLAN architectures to maintain optimal network performance and user experience.

The IEEE 802.11-2016 standard specifies two methods for Fast BSS Transition (FT) to facilitate fast and secure roaming:mrn-cciew

Over-the-Air (OTA):The client communicates directly with the target AP to perform the authentication exchange during roaming.

Over-the-Distribution System (Over-the-DS):The client communicates with the current AP, which then communicates with the target AP over the distribution system to perform the authentication exchange.

These methods are designed to reduce the time required for re-authentication during roaming, ensuring minimal disruption to ongoing sessions.

The CWDP-305 Official Study and Reference Guide states:

"802.11r defines two methods for fast BSS transition: Over-the-Air and Over-the-DS, both aimed at reducing latency during client roaming."

When conducting a predictive site survey, it's essential to configure the simulated APs to reflect the expected real-world conditions.If dynamic Radio Resource Management (RRM) will be utilized, setting the AP transmit power to an estimated average level that matches the expected client devices, such as 25 mW, ensures that the predictive model accurately represents the operational environment.This approach helps in designing a WLAN that provides optimal coverage and performance.

Comprehensive and Detailed Explanation:

Passive RFID tags lack an internal power source and rely on energy transmitted from an RFID reader to power up and communicate. In WLAN designs supporting RTLS, passive tags do not directly communicate with the WLAN infrastructure. Instead, they depend on tag readers to capture their information and relay it to the location server. This design consideration is crucial for accurate asset tracking and management.

Real-Time Location Systems (RTLS) require precise triangulation, which can only occur if a device is detected by at least three APs with strong RSSI values from various angles. The best accuracy is achieved by placing APs around the perimeter and within the area so devices are surrounded.

From CWDP-305:

“For accurate Wi-Fi location tracking, ensure that client devices can be detected by a minimum of three, preferably four, APs with good signal strength. APs should be placed around the perimeter and within the location zone for proper triangulation.”

— Reference: CWDP-305 Official Study and Reference Guide, Chapter on Designing for Specific Applications

In stadium environments where aesthetics are important, using under-seat enclosures for APs is a common practice. These enclosures conceal the APs, protect them from physical damage, and maintain the manufacturer's warranty, as they do not require modifications like painting or unauthorized mounting methods.

Achieving a 450 Mbps data rate in 802.11n requires specific features:

Short Guard Interval (GI):Reduces the interval between symbols from 800 ns to 400 ns, increasing throughput.

40 MHz Channels:Doubles the channel width compared to 20 MHz, allowing more data to be transmitted.

3 Spatial Streams:Utilizes multiple antennas to transmit separate data streams simultaneously, significantly boosting data rates.

While frame aggregation and transmit beamforming enhance performance and reliability, they are not prerequisites for achieving the 450 Mbps MCS rate.

Comprehensive and Detailed Explanation:

Mounting APs above the ceiling can significantly degrade WLAN performance due to signal attenuation and unpredictable RF propagation.If aesthetic constraints were not communicated during the requirements gathering phase, the design likely does not account for the additional attenuation caused by ceiling materials.Therefore, it's essential to inform the stakeholder that the current deployment does not meet performance requirements and that a redesign is necessary to address the unforeseen constraints.Pass4Success

The Bill of Materials (BoM) is a comprehensive list detailing all hardware components, devices, and materials required for the deployment of a WLAN infrastructure. It serves as a reference for procurement and ensures that all necessary items are accounted for before the deployment begins. Unlike the Statement of Work, which outlines the scope and objectives, or the design report, which provides technical specifications, the BoM focuses specifically on the tangible components needed for implementation.

Interference primarily affects the receiver's ability to demodulate signals. In a point-to-point link, RF interference occurring at the middle of the link has little to no impact unless it reaches either endpoint. Therefore, the focus must be on minimizing interference at the receivers.

From CWDP-305:

“Interference at the receiver is the key concern in bridge links. The energy must be received cleanly to enable demodulation, so interference near the receiving AP is more critical than in the link’s midspan.”

— Reference: CWDP-305 Official Study and Reference Guide, Chapter on ProtocolandSpectrum Analysis

Importing a scaled floor plan is one of the very first steps required in wireless design tools. This serves as the canvas upon which walls, attenuation, and APs will be layered. Without a floor plan, no spatial or RF modeling can occur.

From CWDP-305:

“A properly scaled and oriented floor plan is the foundation of a design. It should be imported early in the process before defining wall types, coverage areas, or AP placements.”

— Reference: CWDP-305 Official Study and Reference Guide, Chapter on Wireless Design Process

CAPWAP and DTLS are the type of standards-based encryption used by office extension APs for the traffic tunnel. Office extension APs are wireless access points that can be deployed in remote locations and connect to a central wireless controller via a secure tunnel over the Internet. CAPWAP is the Control and Provisioning of Wireless Access Points protocol, which defines how the wireless controller and the office extension APs communicate and exchange control and data messages. DTLS is the Datagram Transport Layer Security protocol, which provides encryption and authentication for the CAPWAP tunnel. DTLS is based on TLS, but it uses UDP instead of TCP as the transport layer protocol, which makes it more suitable for real-time applications. DTLS protects the CAPWAP tunnel from eavesdropping, tampering, and replay attacks, and ensures the confidentiality and integrity of the wireless traffic. References: CWNP, CWDP Certified Wireless Design Professional Official Study Guide, Configure OEAP and RLAN on Catalyst 9800 WLC, Hardening Microsoft 365, Office 2021, Office 2019 and Office 2016

Active site surveys involve connecting to the WLAN and moving through the environment to assess performance metrics such as throughput and signal strength.During this process, roaming behavior is also observed, as the client device transitions between APs.Evaluating roaming performance is critical to ensure seamless connectivity and optimal user experience.

The CWDP-305 Official Study and Reference Guide emphasizes:

"Active surveys not only measure throughput but also provide insights into client roaming behavior, which is essential for validating network performance."

Comprehensive and Detailed Explanation:

When analyzing a customer's existing infrastructure, obtaining read-only access to certain systems is crucial for gathering information without risking unintended changes. The systems include:

B. RADIUS:Accessing RADIUS servers allows you to review authentication logs and configurations, helping to understand how network access is managed.

C. Switches:Reviewing switch configurations and logs provides insights into network topology, VLAN assignments, and potential bottlenecks.

D. Active Directory:Access to Active Directory helps in understanding user authentication mechanisms, group policies, and organizational units, which are essential for designing access controls.

E. Routers:Examining router configurations and routing tables aids in understanding traffic flow, subnetting, and inter-network connectivity.

A. Clients:Direct access to client devices is generally unnecessary and can pose privacy concerns. Information about client behavior can often be gathered through network monitoring tools.

In wireless networks, devices dynamically adjust their physical layer (PHY) data rates based on the quality of the radio frequency (RF) environment. Several factors influence a device's decision to lower its PHY rate:

Signal degradation: As the signal strength weakens due to distance or obstacles, the device may lower its data rate to maintain a reliable connection.

Interference: The presence of other RF signals can cause interference, leading the device to reduce its data rate to mitigate potential errors.

Retransmissions: An increase in retransmissions indicates that frames are not being successfully received, prompting the device to lower its data rate to improve reliability.

While packet loss is a consequence of these factors, it is not a direct cause for adjusting the PHY rate.

Understanding both the physical layout and logical configuration of the network is critical. The two most helpful documents for that are:

Blueprints:Provide the architectural layout of the facility, including walls, materials, and structural elements that affect RF propagation.

Network Closet Locations:Identify where networking equipment such as switches and patch panels are located for physical cabling and AP backhaul planning.

From CWDP-305:

“Accurate blueprints and physical infrastructure documentation, such as IDF/MDF locations, are essential for physical and logical WLAN planning.”

— Reference: CWDP-305 Official Study and Reference Guide, Chapter on Wireless Design Process

When using predictive design tools for WLAN planning, it's crucial to calibrate the floor plan to ensure accurate distance measurements. This involves setting the scale of the imported floor plan so that the tool can accurately simulate RF propagation and coverage.

The CWDP-305 Official Study and Reference Guide states:

"Before placing APs and other elements, calibrate the floor plan to ensure that distances and areas are accurately represented, which is essential for precise predictive modeling."

Comprehensive and Detailed Explanation:

The "Network Card Simul-ation" feature in site survey software allows the simul-ation of RF data as if it were received by a specific client device.This is particularly useful for assessing uplink performance and understanding how different client devices, with varying antenna gains and sensitivities, would perform in the surveyed environment.By simulating different client types, network designers can ensure that the WLAN design accommodates the performance requirements of all intended client devices.

Comprehensive and Detailed Explanation:

Latency is a critical metric when designing WLANs for VoIP (Voice over IP) applications. High latency can result in poor call quality, including delays and echoes. Industry standards recommend that one-way latency should not exceed 150 milliseconds to maintain acceptable voice quality. Therefore, during site surveys and network design, measuring and minimizing latency is essential to ensure a high-quality VoIP experience.

Comprehensive and Detailed Explanation:

Hiding the Service Set Identifier (SSID) can serve specific purposes, such as:

Preventing guests from attempting to join the secured corporate network:By not broadcasting the corporate SSID, casual users are less likely to attempt connections, reducing unauthorized access attempts.

Minimizing help desk calls from users and guests attempting to join the wrong network:When only the guest network SSID is visible, it simplifies the connection process for visitors, leading to fewer support requests.

However, it's important to note that SSID hiding is not a robust security measure. Determined attackers can still detect hidden networks using various tools, as the SSID can be revealed in certain management frames like probe requests and association requests.

Comprehensive and Detailed Explanation:

The 2.4 GHz band has only three non-overlapping channels: 1, 6, and 11.Using other channels can lead to overlapping and interference.To prevent this, the automatic channel assignment settings should be configured to use only channels 1, 6, and 11, ensuring minimal overlap and optimal performance.

Dynamic Channel Assignment (DCA) algorithms optimize the RF environment by automatically selecting channel assignments based on factors like interference, noise, and utilization. However, DCA requires tuning of algorithm parameters to align with the specific design and site requirements.

From CWDP-305:

“Dynamic channel assignment and transmit power control must be configured according to the design goals and validated after deployment. Default settings may not produce optimal results in all environments.”

Simply relying on default settings without adjustment can lead to poor RF behavior.

— Reference: CWDP-305 Official Study and Reference Guide, Chapter on Wireless Design Process

In high-density environments like stadiums and convention centers, the presence of large crowds significantly impacts Wi-Fi signal propagation.Human bodies, composed mostly of water, absorb and attenuate radio frequency (RF) signals, especially in the 2.4 GHz and 5 GHz bands commonly used by Wi-Fi.This absorption leads to reduced signal strength and potential connectivity issues during events when the venue is filled with people.

Designing a WLAN for such environments requires careful consideration of crowd density and its impact on RF signals.Strategies may include increasing the number of access points (APs), using directional antennas to focus coverage, and conducting site surveys during events to assess real-world performance.

A client-to-AP link imbalance occurs when the AP's transmit power is significantly higher than that of the client device.This disparity can lead to situations where the client can receive signals from the AP but cannot transmit signals back effectively.This imbalance is particularly problematic in environments where clients have limited transmit capabilities, such as battery-powered devices.To mitigate this issue, it's recommended to adjust the AP's transmit power to match the capabilities of the client devices, ensuring balanced communication.

Co-Channel Interference (CCI) occurs when multiple APs on the same channel are heard in the same area, even at relatively low signal levels. CCI is not eliminated simply because signals are below −75 dBm. In fact, CCI is a concern even when APs are heard at levels as low as −85 dBm or lower.

From CWDP-305:

“CCI can be problematic even when the signal from neighboring APs is heard at levels between −85 dBm to −93 dBm. Effective channel planning requires minimizing overlap of same-channel signals at or above these thresholds.”

— Reference: CWDP-305 Official Study Guide, Post-Design ValidationandTroubleshooting Chapter

In cloud-managed WLAN architectures, the standard procedure involves pre-configuring the access point (AP) profiles within the cloud management platform. Once these profiles are set, the APs are connected to the network, where they automatically reach out to the cloud controller to retrieve their specific configurations. This method streamlines deployment, ensuring consistency and reducing manual configuration errors.

Comprehensive and Detailed Explanation:

Transitioning from a centralized to a distributed data forwarding model can introduce compatibility issues. Specifically:

C.Some APs designed for centralized architectures may lack the necessary hardware or firmware capabilities to support distributed forwarding features, such as local breakout or direct client-to-client communication, leading to potential limitations in functionality.

802.11 admission control mechanisms are employed to manage and regulate the bandwidth resources available in a WLAN.By controlling the admission of traffic into the network, these mechanisms ensure that high-priority traffic, such as voice or video, receives the necessary resources for optimal performance.Admission control settings are configured separately for each Access Category (AC), allowing granular control over different types of traffic.

CAPWAP (Control and Provisioning of Wireless Access Points):Modern standard protocol for tunneling management and data frames between APs and WLCs.

GRE (Generic Routing Encapsulation):Sometimes used by vendors as an alternative tunneling method, especially for data transport.

From CWDP-305:

“CAPWAP is the most widely used protocol for communication between access points and controllers. GRE is also utilized in some vendor implementations for tunneling user data.”

— Reference: CWDP-305 Official Study and Reference Guide, Chapter on Infrastructure Design

Comprehensive and Detailed Explanation:

In the "local MAC" variation of the centralized WLAN architecture, all MAC (Media Access Control) functions are performed by the Access Point (AP). A minimal subset of network control is offloaded to the WLAN controller, which also handles management and monitoring functions. This approach allows for more efficient processing at the edge of the network, reducing latency and improving performance.

In environments where both WMM-PS (Wi-Fi Multimedia Power Save) certified and non-WMM-PS client devices coexist, disparities in performance and battery life can occur. WMM-PS enhances power-saving mechanisms by allowing devices to enter low-power states and schedule transmissions efficiently. Non-WMM-PS devices, lacking this capability, rely on traditional power-saving methods like PS-Poll, which are less efficient. As a result, WMM-PS devices benefit from improved battery life and performance, while non-WMM-PS devices may experience reduced efficiency.

Coverage must be validated from the perspective of the least capable or lowest-spec client device expected in the environment. This ensures that all necessary devices—not just the most capable ones—can associate and operate reliably.

From CWDP-305:

“Validating coverage should focus on the least capable client device since it will typically have the weakest radio and lowest sensitivity. This ensures all users can connect and meet performance requirements.”

— Reference: CWDP-305 Official Study Guide, Post-Design Validation Chapter

Comprehensive and Detailed Explanation:

In environments with highly reflective materials, such as manufacturing facilities, the use of Short Guard Intervals (SGI) can lead to increased inter-symbol interference due to multipath propagation. SGI reduces the guard interval from 800ns to 400ns, which can improve throughput in environments with minimal interference. However, in reflective environments, the shorter interval may not provide sufficient time to mitigate the effects of delayed signals, leading to higher error rates. Therefore, it is recommended to disable SGI on the 2.4 GHz band in such environments to maintain reliable communication.

Received Signal Strength Indicator (RSSI) is a metric that measures the power level of a received radio signal.In the context of location-based services within wireless networks, RSSI-based localization is known for its simplicity, as it doesn't require additional hardware or complex algorithms.However, this simplicity comes at the cost of accuracy.RSSI measurements can be significantly affected by environmental factors such as multipath propagation, obstacles, and signal interference, leading to less precise location estimations compared to other methods like AoA, ToA, or TDoA.Wray Castle

Comprehensive and Detailed Explanation:

A signal with a low duty cycle indicates that it is active only for short periods and remains inactive for the majority of the time.Such signals typically have minimal impact on WLAN performance because they occupy the channel infrequently, allowing Wi-Fi transmissions to occur during the inactive periods.Therefore, while it's essential to be aware of such signals, they generally do not pose significant interference to WLAN operations.

In a Single Channel Architecture (SCA), all access points (APs) operate on the same channel and share a virtual Basic Service Set Identifier (BSSID).The wireless controller manages client associations by directing the client to the AP with the strongest Received Signal Strength Indicator (RSSI), ensuring optimal connectivity.

The CWDP-305 Official Study and Reference Guide explains:

"Using a SCA means that all APs will be using the same channel in a given layer. How is the AP with which the client associates determined? C. All APs share a virtual BSSID. A controller will tell the closest AP to the client to communicate with it, since it has a greater RSSI from the client."

Comprehensive and Detailed Explanation:

Enabling the "Validate server certificate" option is a critical security measure when configuring Extensible Authentication Protocol (EAP) types, such as EAP-TLS or PEAP. This setting ensures that the client verifies the authenticity of the RADIUS server's certificate during the authentication process, preventing man-in-the-middle attacks. By validating the server certificate, clients can confirm they are connecting to a legitimate network, thereby maintaining the integrity and security of the WLAN.

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Each SSID broadcast by an AP adds additional management frame overhead, such as beacon frames. These beacon frames are transmitted periodically by the AP at the lowest mandatory data rate (e.g., 1 or 6 Mbps), which consumes airtime that would otherwise be used for client data.

According to CWDP-305:

“Each SSID increases beacon overhead. More SSIDs lead to greater airtime consumption by management traffic, which in turn decreases available throughput for actual client data traffic.”

Reducing the number of SSIDs is a best practice to minimize management overhead and optimize throughput in the wireless network.

— Reference: CWDP-305 Official Study and Reference Guide, Chapter on Infrastructure Design

In a controller-based WLAN infrastructure, when the Wireless LAN Controller (WLC) and Access Points (APs) reside on different subnets, a router is essential to facilitate communication between them.The router enables inter-subnet routing, allowing APs to discover and communicate with the WLC.

The CWDP-305 Official Study and Reference Guide emphasizes the necessity of proper Layer 3 routing for APs to locate and join controllers across different subnets.

If the number of APs changes due to budget constraints, a complete redesign is required to reevaluate coverage, capacity, and performance expectations. Increasing transmit power or relying on 2.4 GHz is not a valid solution, as it can result in co-channel interference and poor roaming.

From CWDP-305:

“A design is based on specific coverage and capacity requirements. Any major change, such as reducing the number of APs, requires a full redesign to determine the impact and ensure that business requirements can still be met.”

— Reference: CWDP-305 Official Study and Reference Guide, Chapter on Wireless Design Process

Comprehensive and Detailed Explanation:

In a WLAN infrastructure, Quality of Service (QoS) markings, such as User Priority (UP) values, are crucial for prioritizing traffic types like voice.When frames are transmitted from the client to the AP (uplink), the client's QoS settings are applied.However, for downlink traffic (from the AP to the client), the AP relies on QoS markings received from the upstream network.If any device in the wired network path, such as switches or routers, does not trust or properly handle these QoS markings, it can strip or alter them.As a result, the AP may transmit downlink frames without the correct UP values, leading to degraded voice quality.

In large enterprise WLAN deployments, efficient IP address and VLAN assignment is crucial for scalability and performance. Common and recommended methods include:

Static VLAN Assignment per SSID:Each SSID is mapped to a specific VLAN, allowing for straightforward traffic segregation.

Dynamic VLAN Assignment via AAA:Utilizing RADIUS servers to assign VLANs based on user credentials or group memberships provides flexibility and centralized control.

VLAN Pooling:Assigning IP addresses from multiple VLANs in a round-robin fashion helps distribute clients evenly and prevents DHCP exhaustion.

However, assigning VLANs based on real-time radio signal metrics like RSSI or SNR is not a standard or recommended practice. Such metrics are variable and can lead to inconsistent VLAN assignments, complicating network management and potentially affecting client performance.

Configuration backups are a critical component of operational and maintenance plans.They ensure that, in the event of a failure or misconfiguration, the network can be restored to a known good state quickly.Despite their importance, configuration backups are often overlooked, leading to prolonged downtimes and increased recovery times during network issues.

Comprehensive and Detailed Explanation:

In voice over WLAN (VoWLAN) deployments, seamless roaming is critical to maintain call quality. As users move throughout the office, their devices must transition between access points without dropping the call or experiencing latency. Therefore, ensuring efficient and fast roaming capabilities is paramount in the design of a WLAN intended to support voice applications.

Comprehensive and Detailed Explanation:

In warehouse environments, physical changes can significantly impact WLAN performance. Over time, the addition or rearrangement of inventory (e.g., pallets, shelving) can alter RF propagation, leading to coverage gaps or interference. Therefore, it's essential to inquire about any inventory changes that may have occurred since the initial installation.

Other Options:

A.DHCP lease exhaustion typically affects IP address assignment but is less likely to cause location-specific WLAN issues.

B.Changes in receive gain are hardware-related and less common unless equipment has been replaced or reconfigured.

D.While rogue APs can cause interference, they usually affect broader areas and are less likely to cause isolated issues unless specifically deployed nearby.

Wi-Fi Multimedia (WMM) is a feature that enables Quality of Service (QoS) on 802.11 networks, allowing for the prioritization of different types of traffic such as voice, video, and data. If WMM is not enabled, the network cannot differentiate or prioritize traffic types, leading to potential performance issues, especially for latency-sensitive applications like VoIP or video conferencing. Therefore, without WMM, 802.11 QoS functionalities are unavailable, impacting the overall efficiency and user experience of the WLAN.

PMK caching(Pairwise Master Key caching) is a roaming technology where the access point (AP) stores the PMK derived during the initial authentication of a client station (STA).If the client roams away and then returns to the same AP, the stored PMK allows for a quicker re-association without the need for a full authentication process.

This mechanism enhances roaming efficiency by reducing latency during re-association, which is particularly beneficial for applications sensitive to delays, such as VoIP.

Channels 116-124 in the 5 GHz band fall under the Dynamic Frequency Selection (DFS) range. These channels are shared with radar systems, such as those used by airports. When radar activity is detected, Access Points (APs) operating on DFS channels must vacate the channel, leading to potential disruptions in service. In environments near airports, it's advisable to avoid using DFS channels to prevent such interruptions, ensuring a stable and reliable wireless experience for voice devices.

An AP-on-a-Stick (APoS) survey is a method used to validate predictive WLAN designs by temporarily placing an access point at the planned installation location and measuring its performance in the actual environment. This approach helps in confirming the accuracy of the predictive model and ensures that the AP placement will meet the desired coverage and performance requirements.

A Non-Disclosure Agreement (NDA) is a legal contract that establishes a confidential relationship between parties. In the context of WLAN design, it ensures that any proprietary information shared by the customer during the information-gathering phase remains confidential and is not disclosed to unauthorized parties.

Non Disclosure Agreements

The Statement of Work (SoW) outlines the tasks and deliverables of the project but does not address confidentiality.

The Bill of Materials (BoM) lists the required components for the project but does not pertain to information protection.

A Hold Harmless agreement typically pertains to liability and indemnification, not confidentiality.

For long-distance point-to-point wireless links, such as those spanning over 1000 yards, directional antennas are preferred due to their focused beamwidth and higher gain.Yagi antennas are a type of directional antenna known for their high gain and narrow beamwidth, making them suitable for such applications.While panel and patch antennas are also directional, Yagi antennas are specifically designed for long-range communications.

Comprehensive and Detailed Explanation:

Real Time FFT stands for Real Time Fast Fourier Transform.It is a spectrum analysis tool that displays the maximum signal amplitude detected at each frequency in real time.This visualization helps in identifying transient RF events, such as sporadic interference or brief signal spikes, which might not be captured in averaged spectrum analyses.By providing immediate feedback on the RF environment, Real Time FFT graphs are invaluable for troubleshooting and optimizing WLAN performance.

A Non-Disclosure Agreement (NDA) is a legal contract that establishes a confidential relationship between parties.In the context of WLAN design, an NDA ensures that any proprietary or sensitive information shared by the customer during the information-gathering phase is kept confidential and not disclosed to unauthorized parties.This agreement builds trust between the service provider and the customer, facilitating open communication and information sharing necessary for effective WLAN design.

To ensure that Access Points (APs) are installed in the exact locations specified in the design, it's essential to use visual aids and physical markers.Cameras can capture images of the intended installation sites, and marking tools can be used to indicate precise mounting locations on-site.This approach minimizes errors during installation and ensures adherence to the design plan.

The CWDP-305 Official Study and Reference Guide highlights the use of such tools:

"Use cameras and marking tools to document and indicate AP placement, ensuring accurate installation according to the design."

An active site survey involves connecting a client device to the WLAN and measuring various performance metrics such as throughput, latency, and roaming behavior. This type of survey is essential for validating that roaming is functioning as intended, as it allows the surveyor to observe the client's ability to maintain a stable connection while moving between access points.

In outdoor environments, channel contention, co-channel interference (CCI), and adjacent channel interference (ACI) can negatively affect bridge performance. The most effective method for identifying usable channels is through a site survey, which includes spectrum analysis at both endpoints.

From CWDP-305:

“Performing an outdoor site survey is critical for point-to-point deployments. This reveals existing RF usage in the area, allowing the selection of channels with minimal interference for optimal link stability.”

— Reference: CWDP-305 Official Study and Reference Guide, Chapter on Advanced Site Surveys

In the 2.4 GHz band, there are only three non-overlapping channels (1, 6, 11). Overuse of radios on the same or overlapping channels results in excessive co-channel interference (CCI), leading to contention and degraded throughput. The CWDP-305 Study Guide advises minimizing the number of active radios in the 2.4 GHz band in dense environments.

Turning off 2.4 GHz radios on some APs is the recommended action to reduce CCI without introducing adjacent-channel interference (ACI), which would occur if you used overlapping channels like 3, 4, or 8. This adjustment retains channel reuse efficiency and supports low-density legacy devices. It’s especially relevant in designs that primarily target 5 GHz or 6 GHz but include 2.4 GHz for backward compatibility.

When establishing a long-distance wireless bridge, such as one spanning 13 kilometers, it's crucial to consider the Fresnel Zone, which is the elliptical area around the line-of-sight path between two antennas. Obstructions within this zone can cause signal degradation due to diffraction.

One significant factor affecting the Fresnel Zone over long distances is the Earth's curvature, commonly referred to as the Earth bulge. As the distance between the two points increases, the Earth's surface curves away, potentially intruding into the Fresnel Zone and obstructing the signal path. Therefore, engineers must calculate the Earth's bulge and ensure that antenna heights are sufficient to maintain a clear Fresnel Zone.

While Free Space Path Loss (FSPL), antenna gain, and receiver sensitivity are essential parameters in link budget calculations, they do not directly address the physical clearance required in the Fresnel Zone.

This is a classic example of a WLAN designed for coverage but lacking capacity. Simply adding more APs without proper planning (option C) or increasing output power (option D) would likely lead to channel contention, co-channel interference, and degraded performance.

A proper redesign would include:

Evaluating user density

Planning for spatial reuse

Implementing low-power, high-density AP placement

Selecting appropriate channels and RF tuning

From CWDP-305:

“High-density environments such as auditoriums require WLANs designed for capacity, not just coverage. This includes AP placement optimization, channel planning, and potentially microcell designs to manage client load effectively.”

— Reference: CWDP-305 Official Study and Reference Guide, Chapter on Designing for Specific Applications

During a successful client roam between APs (when connected), the client typically sends a Reassociation Request to the new AP, and the AP responds with a Reassociation Response. This sequence helps maintain the client session, including IP addressing and encryption state.

From CWDP-305:

“Roaming involves a Reassociation Request from the client and a Reassociation Response from the new AP. These frames are critical markers of a successful handoff in active WLANs.”

— Reference: CWDP-305 Official Study and Reference Guide, Chapter on Post-Design ValidationandTroubleshooting

Comprehensive and Detailed Explanation:

Supporting over 300 devices with only two APs in a high-density environment like a convention center auditorium is inadequate.Simply adding more APs without a proper design can lead to co-channel interference and other issues.A comprehensive redesign is necessary to ensure appropriate AP placement, channel planning, and capacity to handle the high number of concurrent clients effectively.

In wired networks, VLANs (Virtual Local Area Networks) are used to segment network traffic into separate broadcast domains, effectively isolating traffic for security and performance purposes.Each VLAN operates as its own distinct network segment.

In wireless networks, while VLANs are used to segregate traffic once it reaches the wired infrastructure, the wireless medium itself is inherently a shared medium.This means that, over the air, all wireless clients share the same RF space, and broadcasts are received by all clients regardless of VLAN assignment.Therefore, VLANs in wireless networks do not inherently provide the same level of broadcast domain separation as in wired networks.

Allowing employees to use their own devices on the company network—commonly known as BYOD (Bring Your Own Device)—can provide several operational benefits:

Enhanced Productivity:Users are more familiar and comfortable with their personal devices, leading to faster adoption and efficiency.

Decreased Costs:The organization can reduce capital expenditures on hardware purchases and lifecycle management.

Increased Satisfaction:Employees prefer working on familiar platforms, which contributes to higher morale and satisfaction.

From the CWDP-305 guide:

“BYOD deployments can enhance user satisfaction and productivity while reducing costs associated with device provisioning. However, they require proper security and access controls.”

— Reference: CWDP-305 Official Study and Reference Guide, Chapter on Wireless Design Process

Comprehensive and Detailed Explanation:

Short ASCII passphrases, especially those 12 characters or fewer, are more vulnerable to dictionary attacks. Attackers can use precomputed tables or brute-force methods to guess these passphrases, especially if they are common or simple. The WPA/WPA2-Personal security model relies on the strength of the passphrase; thus, longer and more complex passphrases significantly enhance security.

Option B:The strength of group keys in a BSS is not directly affected by the length of the passphrase but rather by the encryption protocols in use.

Option C:Regardless of the passphrase length, the Pairwise Master Key (PMK) derived is 256 bits.

Option D:Most AP and client vendors support ASCII-based passphrase entry, making this option incorrect.

In Europe, the 2.4 GHz band includes channels 1 through 13, whereas in North America, channels 12 and 13 are typically not used due to regulatory restrictions.If the AP in the hotel room is operating on channel 13, a laptop configured for North American standards may not detect or connect effectively to that channel, resulting in a low Received Signal Strength Indicator (RSSI).

The CWDP-305 Official Study and Reference Guide explains:

"Client devices configured for specific regulatory domains may not support all channels available in other regions. This can lead to connectivity issues when devices encounter channels that are not permitted in their configured domain."

Therefore, the most likely cause of the low RSSI is the client's inability to properly connect to the AP operating on channel 13, leading it to associate with a more distant AP on a different channel, hence the weaker signal.

The ability to locate a client device using WLAN infrastructure relies on the client actively transmitting frames that can be detected by multiple access points. These frames are typically management or data frames used during association, authentication, or normal operation.

If the client device is turned off, it is not transmitting any 802.11 frames. Therefore, the infrastructure cannot detect or triangulate its location using standard methods such as RSSI (Received Signal Strength Indicator) or time difference of arrival.

According to the CWDP-305 Official Study and Reference Guide (Chapter: Designing for Specific Applications), location-based services (LBS) are dependent on the active participation of the client device. Without beacon frames, probe requests, or any other 802.11 activity, no positioning data can be gathered.

“Client devices must be actively transmitting for their location to be calculated through triangulation or trilateration. If a device is powered off, it cannot be tracked by the WLAN infrastructure.”

— Reference: CWDP-305 Official Study and Reference Guide, Chapter on Designing for Specific Applications

Comprehensive and Detailed Explanation:

Mounting APs above the ceiling can significantly degrade WLAN performance due to signal attenuation caused by ceiling materials and obstructions. If aesthetic requirements were not communicated during the initial requirements gathering, the current deployment does not align with the documented design specifications. The appropriate course of action is to inform the stakeholder that the WLAN performance requirements may not be met under the current installation and that a new design process is necessary to address the aesthetic constraints while ensuring optimal performance.

Project parameters in WLAN design software typically include requirements and constraints like:

Minimum required signal strength (e.g., –67 dBm for VoIP)

Minimum required SNR

Desired data rate coverage

These are configured before design work begins and guide how AP placement and coverage will be modeled.

From CWDP-305:

“Project parameters such as minimum signal strength, data rate, and required SNR must be defined before the actual placement of access points. These values define the target RF environment.”

— Reference: CWDP-305 Official Study and Reference Guide, Chapter on Wireless Design Process

When deploying a WLAN that includes both WMM-PS (Wi-Fi Multimedia Power Save) certified devices and legacy devices that do not support WMM, it's important to understand the implications on performance and battery life.

WMM-PS, based on Unscheduled Automatic Power Save Delivery (U-APSD), allows client devices to conserve battery power by managing the time the device spends in sleep mode and reducing the need for frequent wake-ups.This mechanism is particularly beneficial for applications like VoIP, where timely delivery of packets is crucial.

However, legacy devices that do not support WMM-PS rely on older power-saving mechanisms, such as PS-Poll, which are less efficient.When both WMM-PS and non-WMM-PS devices operate on the same WLAN, the differences in power-saving capabilities can lead to inconsistencies in performance and battery life.Specifically, WMM-PS devices may experience better battery conservation and performance, while non-WMM-PS devices may have reduced efficiency.

This scenario is addressed in the CWDP-305 Official Study and Reference Guide, which emphasizes the importance of understanding client capabilities and their impact on WLAN performance.

When APs are deployed in the same physical pattern across floors without channel and physical spacing considerations, co-channel interference (CCI) between floors occurs. This is particularly problematic when APs on different floors are vertically aligned on the same channels.

From CWDP-305:

“In multi-floor deployments, avoid placing APs on the same vertical axis across floors using the same channel. This leads to CCI. Stagger AP locations and vary channels to reduce interference.”

— Reference: CWDP-305 Official Study Guide, Wireless Design Process Chapter

Comprehensive and Detailed Explanation:

When conducting a predictive or passive RF site survey using survey software, accurately scaling the map is a critical initial step. Without proper scaling, distance and RF propagation calculations will be inaccurate, leading to flawed design outcomes.

“Scaling the map is a required step before placing APs, drawing walls, or runningsimul-ations in predictive tools. All distance-based calculations rely on this reference.”

— CWDP-305 Study Guide, Chapter: Advanced Site Surveys

When conducting a site survey, accurately determining ceiling heights is crucial for proper AP placement and coverage prediction.If ladder use is restricted, utilizing a laser distance meter provides a precise and cost-effective solution.Laser measures can quickly and safely determine vertical distances without the need for physical elevation.گروه آموزشی و پژوهشی سیب

The CWDP-305 Official Study and Reference Guide emphasizes:

"Laser distance meters are valuable tools during site surveys, allowing for accurate measurements of ceiling heights and other distances without the need for ladders or lifts."

If a persistent source of interference cannot be removed, the best course of action is to design around it—usually by changing channels to avoid the affected frequencies. This minimizes the impact on WLAN operation while still coexisting with the interfering device.

From CWDP-305:

“If interference is detected during post-deployment validation and cannot be mitigated by removal, channel reallocation is the most effective way to work around the problem without affecting WLAN integrity.”

— Reference: CWDP-305 Official Study Guide, Post-Design ValidationandTroubleshooting

Centralized data forwarding means all wireless traffic is tunneled back to a central controller, which handles tasks such as filtering, firewalling, and policy enforcement.

From CWDP-305:

“Centralized data forwarding enables consistent policy enforcement and traffic filtering by handling all traffic at the controller rather than at individual APs.”

This approach provides better control and visibility, especially in environments with strict security and traffic management requirements.

— Reference: CWDP-305 Official Study and Reference Guide, Chapter on Infrastructure Design

Comprehensive and Detailed Explanation:

Voice over WLAN (VoWLAN) applications are sensitive to packet loss, which can degrade call quality. An acceptable packet error rate (PER) for VoWLAN is typically no more than 1%. Maintaining a PER at or below this threshold ensures that voice communications remain clear and intelligible, minimizing the impact of lost packets on the user experience.

A specification sheet (spec sheet) provides detailed technical capabilities of a device, including supported Wi-Fi standards (e.g., 802.11a/b/g/n/ac/ax), number of spatial streams, band support, and security protocols. This helps WLAN designers understand performance expectations and compatibility.

From CWDP-305:

“Specification sheets are critical for evaluating client capabilities. They include information about supported frequency bands, maximum data rates, MIMO capabilities, and supported security protocols.”

— Reference: CWDP-305 Official Study and Reference Guide, Chapter on Wireless Design Process

Wi-Fi 6E introduces access to the 6 GHz spectrum, which provides a significantly larger number of non-overlapping 20 MHz, 40 MHz, and even 80 MHz and 160 MHz channels than the 5 GHz band. This abundance of spectrum allows channel bonding (e.g., 40 MHz) with minimal adjacent channel interference (ACI).

From CWDP-305:

“The availability of contiguous spectrum in the 6 GHz band allows for wider channels, such as 40 MHz and 80 MHz, to be used more frequently without interference issues seen in the 5 GHz band.”

— Reference: CWDP-305 Official Study and Reference Guide, Chapter on Designing for Specific Applications

Comprehensive and Detailed Explanation:

In a Point-to-Multipoint (PtMP) setup where one building serves as the central hub (root bridge) connecting to multiple other buildings arranged in a square, a100° sector antennais ideal. This type of antenna provides a wide coverage area, allowing it to effectively communicate with all the other buildings positioned around it. Sector antennas focus the RF energy in a specific direction, offering better performance and reduced interference compared to omni-directional antennas in such scenarios.

In environments with low Signal-to-Noise Ratio (SNR), maintaining reliable communication becomes challenging due to increased potential for errors.Receive Diversityis a technique employed to enhance signal reception under such conditions.

Receive Diversity involves using multiple antennas at the receiver to capture the same signal.By combining these multiple received signals, the system can mitigate the effects of fading and interference, effectively improving the SNR.This enhancement leads to better throughput as the likelihood of retransmissions due to errors decreases.

Other options like 64-QAM require high SNR to function effectively, and A-MSDU frame aggregation is more beneficial in high SNR environments where larger frames can be transmitted without significant error.

To authenticate users against an LDAP database for WLAN access, a RADIUS (Remote Authentication Dial-In User Service) server must be implemented. RADIUS acts as an intermediary between the WLAN infrastructure and the LDAP directory, facilitating authentication requests. When a user attempts to connect to the WLAN, the access point forwards the authentication request to the RADIUS server, which then queries the LDAP directory to verify the user's credentials. This integration ensures centralized authentication and enhances security by leveraging existing directory services.

Comprehensive and Detailed Explanation:

The 802.11 amendments that address regulatory and transmission requirements are:

C. 802.11d:This amendment provides country-specific information, allowing devices to operate in compliance with local regulations regarding frequency use and power levels.

E. 802.11h:Introduced to address spectrum and transmission power management in the 5 GHz band, this amendment includes features like Dynamic Frequency Selection (DFS) and Transmit Power Control (TPC) to mitigate interference with radar systems and adhere to regulatory requirements.

A. 802.11kfocuses on radio resource management.

B. 802.11ipertains to security enhancements.

D. 802.11fdeals with inter-access point protocol for roaming.

The IEEE 802.11y amendment introduced support for operation in the 3.65–3.7 GHz frequency band, allowing for higher power transmissions up to 20 watts Equivalent Isotropically Radiated Power (EIRP).This enhancement was designed to improve wireless coverage and performance, especially in environments requiring extended range and penetration.

The increased power and frequency range provided by 802.11y facilitate better service in areas where traditional Wi-Fi bands may be congested or less effective.