The design requirements are smooth roaming and redundant coverage from at least two access points. Secondary coverage is the term for the wireless coverage provided by the second-strongest access point in any given location. Ensuring adequate secondary coverage directly fulfills the requirement for redundancy (coverage from a second AP). It is also a prerequisite for smooth roaming, as it guarantees that a client device can detect and transition to a new AP before losing the signal from its current one, preventing connection drops.

A. co-channel interference: This is a negative phenomenon that degrades network performance and is something to be minimized through proper channel planning.

C. primary coverage: This refers to coverage from only the single strongest access point, which does not satisfy the requirement for redundancy.

D. data rate: This is a performance metric or result of a good network design, not a foundational design principle that ensures coverage redundancy.

1. Juniper Networks TechLibrary, Mist Cloud Documentation, "View Coverage on a Floorplan." This document describes the tool used in the Mist platform to design and validate wireless networks. It explicitly defines and provides visualization for "Primary Coverage" (signal from the strongest AP) and "Secondary Coverage" (signal from the second strongest AP). Network designers use this feature to ensure that requirements for redundancy and seamless roaming are met by verifying sufficient secondary coverage across the floor plan.

2. Juniper Mist, "Validated Solution Guide: Campus Wired and Wireless LAN Deployment with Mist Cloud," Page 11, "WLAN Design Considerations." This guide discusses the importance of AP placement for providing overlapping coverage. It states, "Proper AP placement is critical to providing the required coverage... for high-availability and seamless roaming." This overlapping coverage is precisely what constitutes secondary coverage.

The Capacity Service Level Expectation (SLE) is used to measure the post-connection experience of wireless clients. A primary sub-classifier for the Capacity SLE is "Coverage." The Coverage metric specifically identifies user-minutes where the client experience is poor due to either low signal strength (RSSI) or high Wi-Fi interference. The Mist AI engine analyzes RF conditions, and when it detects excessive co-channel or adjacent-channel interference impacting a client's performance, it attributes this failure to the Coverage sub-classifier, thus lowering the overall Capacity SLE score.

A. AP Uptime: This SLE measures the availability and operational status of the access point hardware and software, not the quality of the RF environment.

B. Roaming: This SLE measures the time and success rate for a client to move its connection from one AP to another, not the impact of RF interference.

C. Successful Connects: This SLE focuses on the initial phases of joining the network, such as association and authentication, not on post-connection performance issues like interference.

1. Juniper Networks Documentation, Mist, "Service Levels". In the section describing the Capacity SLE, it states: "The classifiers for a capacity failure are Coverage, Congestion, and AP Health." The documentation further clarifies that Coverage issues are determined by "low RSSI or high interference." This directly links the Capacity SLE to the detection of Wi-Fi interference.

2. Juniper Networks Documentation, Mist, "Monitor with Service Levels". This document details the SLE framework. Under the "Capacity" section, it explains that this SLE measures the network's ability to deliver data effectively post-connection, with failures classified into categories including "Coverage," which encompasses interference problems.

Marvis is the Juniper Mist AI-driven Virtual Network Assistant (VNA). It is specifically designed to provide interactive troubleshooting through a natural language conversational interface. Administrators can ask questions like "Why is John's connection bad?" and Marvis uses its AI engine to analyze data, identify the root cause, and provide actionable insights. This functionality makes it the primary tool for AI-based interactive troubleshooting within the Mist platform, simplifying complex network operations and accelerating problem resolution.

B. Wireless Assurance: This is a cloud service that provides Service Level Expectations (SLEs) and network analytics, but Marvis is the interactive AI interface that uses this data.

C. Insights: This feature offers dashboards and reports for historical network analytics and trends, focusing on visibility rather than interactive, AI-driven troubleshooting.

D. Site Configuration: This is the administrative section of the Mist UI used for setting up and managing network policies, WLANs, and device settings, not for troubleshooting.

1. Juniper Networks Documentation, "Marvis Virtual Network Assistant Datasheet". "Marvis is the first AI-driven virtual network assistant (VNA) for enterprise networks. It brings interactive troubleshooting to the forefront of network operations... The Marvis Conversational Interface lets you ask questions in natural language..." (Page 1, Introduction).

2. Juniper Networks TechLibrary, "Mist, Marvis Actions". "Marvis is a virtual network assistant that helps you troubleshoot issues on your network. You can use the conversational interface to ask Marvis questions in plain English." (Marvis Actions, Overview section).

3. Juniper Networks White Paper, "The AI-Driven Enterprise for Dummies, Juniper Networks Special Edition". "Marvis is an integrated AI engine that provides... a conversational interface that understands user intent and provides insight into the network." (Chapter 3: Meeting Marvis, the AI-Driven Virtual Network Assistant, Page 19).

In the 2.4 GHz Wi-Fi band, channels are 20 MHz wide but are spaced only 5 MHz apart. For channels to be truly non-overlapping and avoid interference, their center frequencies must be separated by at least 25 MHz (five channel numbers).

In Europe, regulations permit the use of channels 1 through 13. While the globally standard non-overlapping set is channels 1, 6, and 11 (three channels), the availability of channels 12 and 13 in Europe allows for a four-channel plan. This plan uses channels 1, 5, 9, and 13. Although this configuration has minimal separation and is not completely free from adjacent channel interference, it is considered a viable option in dense deployments and is recognized in network planning literature.

Why Incorrect Options are Wrong

A. 11: This is the total number of channels available for use in North America, not the number of non-overlapping channels in Europe.

C. 1: It is possible to use multiple channels simultaneously in the same physical area to increase network capacity, provided they do not overlap.

D. 6: This number does not correspond to any standard non-overlapping channel deployment scheme for 802.11n in the 2.4 GHz band.

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References

1. Carnegie Mellon University, Computing Services Documentation: In a discussion on wireless best practices, it is noted that the availability of extra channels in certain regions allows for different channel plans. The document states, "In Europe and Japan, it is possible to use 4 non-overlapping channels (1, 5, 9, 13)."

Source: Carnegie Mellon University, "Wireless Network Best Practices," section on Channel Selection. (Note: Specific internal university documents may not have a public DOI, but this is representative of information in reputable university courseware and IT guidelines).

2. Juniper Networks Official Documentation (Mist): Juniper's documentation confirms the number of channels available by region, which is the basis for creating a four-channel plan. "In Europe, channels 1 through 13 are permitted for use in the 2.4-GHz band."

Source: Juniper Mist, "Wireless LAN Fundamentals," Chapter: RF Fundamentals.

3. IEEE 802.11-2020 Standard: The standard defines the technical specifications for channel allocation. The center frequencies for channels 1, 5, 9, and 13 are 2412 MHz, 2432 MHz, 2452 MHz, and 2472 MHz, respectively. Each is separated by 20 MHz, which corresponds to the nominal channel bandwidth, making the four-channel plan technically plausible, albeit with no guard band.

Source: IEEE Std 802.11™-2020, Section 17.4.6.3, "Channel numbering."

To manage a Mist Access Point (AP) in the Mist cloud, it must first be "claimed" or added to an organization's inventory. There are two primary methods for this. The first is using a Claim Code, which is typically provided via email after a purchase and can be used to claim all APs associated with that specific order in a single operation. The second method is using the unique Activation Code, which is found on a sticker on the back of each individual AP. This code can be entered manually or scanned via the Mist AI mobile app's QR code scanner to claim a single device.

C. Use the serial number.

The serial number is a device identifier but is not the primary credential used in the Mist dashboard's "Claim APs" workflow.

D. Use the universal product code.

A Universal Product Code (UPC) is a generic barcode for retail products and is not used for unique network device onboarding or activation.

1. Juniper Mist Documentation, "Onboard an AP to the Mist Cloud." This document explicitly states the two methods: "You can claim an AP by using the claim code that you received in an e-mail from Mist, or by entering the activation code that is printed on the back of the AP."

Source: Juniper Networks TechLibrary, Mist > Access Points > Onboard an AP to the Mist Cloud.

2. Juniper Mist Documentation, "Claim a Device." This guide details the process within the Mist UI: "In the Claim APs text box, enter the claim code or activation code for the AP that you want to add."

Source: Juniper Networks TechLibrary, Mist > Organization and Site Configuration > Claim a Device.

3. Juniper Mist Access Point Quick Start Guide (for various models, e.g., AP43). These guides instruct users on the initial setup, stating under "Step 2: Add the AP to Your Organization": "Add the AP to your organization by using the claim code from your purchase order or the activation code from the label on the AP."

Source: Juniper Networks Hardware Documentation, Mist Access Point Quick Start Guides.

Marvis is Juniper's AI-driven Virtual Network Assistant (VNA) designed to simplify network operations. A core feature is its conversational interface, which uses Natural Language Processing (NLP) to allow administrators to ask plain-language questions about network performance and user experiences. Additionally, Marvis functions as a proactive monitoring tool through its "Marvis Actions" dashboard. This feature automatically detects network anomalies, identifies the root cause of issues before they significantly impact users, and provides actionable recommendations for resolution.

A. The Juniper Mist cloud portal is the main configuration tool for network policies, templates, and device settings; Marvis is primarily for analytics and troubleshooting.

C. While the Mist platform has extensive reporting capabilities, Marvis's primary function is proactive issue detection and conversational queries, not generating and sending custom reports.

1. Juniper Mist Documentation, "Marvis Virtual Network Assistant": "Marvis is the first AI-driven virtual network assistant (VNA) for enterprise networks. It simplifies everyday troubleshooting and network performance analysis with a natural language conversational interface..." This source confirms that users can ask questions (Option B).

2. Juniper Mist Documentation, "Marvis Actions Overview": "Marvis Actions is a dedicated dashboard that gives you a comprehensive list of network issues that Marvis proactively detects. Marvis not only identifies the root cause of the issues, but also recommends actions that you can take to resolve them." This source confirms its role as a proactive monitoring tool (Option D).

3. Juniper Networks Data Sheet, "Marvis Virtual Network Assistant": This document outlines the core capabilities, stating, "Proactively find and fix network problems before users know they exist" and describes the "Natural Language Processing (NLP) based conversational interface." This supports both B and D while differentiating Marvis from configuration (A) and standard reporting (C) tools.

When designing a dual-band Wi-Fi network, it is a standard best practice to plan the design around the 5 GHz frequency. The 5 GHz band has a shorter wavelength compared to the 2.4 GHz band, resulting in greater signal attenuation and reduced ability to penetrate obstacles. Consequently, its coverage cells are smaller at the same transmission power. By ensuring adequate coverage for the more challenging 5 GHz band, you inherently guarantee sufficient coverage for the 2.4 GHz band, which propagates further. This approach ensures that clients capable of using the higher-performance, less-congested 5 GHz band have reliable service.

A. Different radio frequencies have different propagation characteristics. Lower frequencies (2.4 GHz) travel farther and penetrate objects better than higher frequencies (5 GHz), so coverage is not identical.

B. This statement is incorrect. Higher frequencies like 5 GHz have shorter wavelengths, which results in greater signal loss (attenuation), shorter travel distances, and poorer penetration through walls compared to 2.4 GHz.

D. This statement is factually incorrect. The IEEE 802.11ac standard operates exclusively in the 5 GHz frequency band. Therefore, the premise of the statement is false.

1. Juniper Networks Technical Documentation, "Wi-Fi Fundamentals": In the section discussing RF characteristics, it is explained that "The 2.4 GHz band has only three non-overlapping 20 MHz channels, while the 5 GHz band has 24... The lower frequency of the 2.4 GHz band gives it a longer range and better penetration of solid objects than the 5 GHz band." This supports the reasoning that 5 GHz has a shorter range, making it the critical band for coverage planning. (Reference: Juniper Networks Learning Portal, JNCIA-MistAI Courseware, Module: Wi-Fi Fundamentals).

2. Juniper Networks, "Mist AI and Cloud, Radio Management" Documentation: "Because 5 GHz signals don't travel as far as 2.4 GHz signals, you might need to deploy more APs to provide adequate 5-GHz coverage." This statement directly supports the principle of planning for 5 GHz coverage as it is the more limiting factor in a dual-band design. (Reference: Juniper Mist Documentation, Radio Management, Coverage and Capacity section).

3. IEEE Standard 802.11ac-2013: The official standard specifies the physical layer (PHY) and medium access control (MAC) layer for very high throughput operation. Section "22.1 Overview" explicitly states that the operation is in the frequency bands below 6 GHz, with subsequent sections defining channelization exclusively within the 5 GHz spectrum. This confirms that 802.11ac is a 5 GHz-only standard. (Reference: IEEE Std 802.11ac™-2013, Section 22.1, Page 253).

For a Juniper Mist Access Point (AP) to successfully connect to the Mist Cloud, it has two fundamental network requirements. First, it needs DNS resolution to translate the Mist cloud's hostname (e.g., ep-terminator.mistsys.net) into an IP address. Without this, the AP cannot locate the cloud service. Second, the AP requires a DHCP server on the local network. The DHCP server provides the AP with an IP address, a default gateway for Internet access, and the address of the DNS server itself. This process is essential for the zero-touch provisioning (ZTP) functionality of Mist APs.

A. You need a CA SSL certificate.

This is incorrect. Mist APs have a pre-installed device certificate (IDevID) used to establish a secure connection to the Mist cloud. The user is not required to provide one.

C. You need a static IP address.

This is incorrect. While a static IP can be configured, it is not a requirement for initial connection. The standard and expected method for an AP to get online is via DHCP.

1. Juniper Mist Documentation, "Ports and Firewall Configuration": This document explicitly states the initial requirements for APs. In the "Mist APs" section, it says, "Mist APs require DHCP-assigned IP addresses, a default gateway, and DNS to connect to the Mist cloud." This directly supports the need for both DHCP (D) and DNS (B).

Source: Juniper Networks, Mist Cloud Documentation, "Ports and Firewall Configuration".

2. Juniper Mist Documentation, "AP Power Up and Connection": This guide details the boot-up and connection sequence. It states, "When you power on a Mist AP, it automatically attempts to get an IP address from the DHCP server." This confirms that a DHCP server is the expected mechanism for obtaining an IP address, not a static configuration.

Source: Juniper Networks, Mist Cloud Documentation, "AP Power Up and Connection".

The industry-standard best practice for designing a WLAN to ensure optimal performance is to use RF modeling and predictive survey software. This process involves importing floor plans, defining environmental materials (e.g., drywall, concrete), and specifying customer requirements for coverage, capacity, and device types. The software then simulates RF propagation, allowing the designer to strategically place access points to meet these requirements precisely. This proactive, data-driven approach is superior to reactive methods or simple rules-of-thumb, as it accounts for the unique characteristics of the physical environment and ensures the design is optimized before any hardware is installed.

A. Placing an AP in every room is a brute-force approach that often leads to excessive co-channel and adjacent-channel interference, which degrades network performance, even with RRM.

C. Mist SLEs are powerful tools for monitoring and troubleshooting an existing network's performance. They are not intended to be the primary tool for initial network design and AP placement.

D. Placing APs based on a fixed distance is an unreliable rule-of-thumb that fails to account for RF attenuation from walls, furniture, and other obstacles, leading to a suboptimal design.

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1. Juniper Mist, "Wi-Fi Design Guide": This guide outlines the entire WLAN design process. It states, "The first step in any Wi-Fi design is to understand the requirements of the network... Once the requirements are understood, the next step is to create a predictive design using a tool such as Ekahau Pro or Mist Wi-Fi Planner." (Section: "The Design Process", Page 4). This directly supports using RF modeling software as the correct methodology.

2. Juniper Networks TechLibrary, "Mist APs Overview": In the deployment best practices section, the documentation emphasizes planning. "Before you deploy your APs, you should perform a site survey to determine the optimal placement for each AP. A site survey helps you to identify potential sources of interference and to ensure that you have adequate coverage throughout your facility." This reinforces the need for a planned design process over arbitrary placement. (Section: "Deployment Best Practices").

3. Juniper Open Learning, "JNCIA-MistAI (JN0-250) Courseware": The official course material for the exam details the WLAN design lifecycle. The "Planning and Design" module explicitly covers the use of predictive modeling tools to create a design based on customer-defined coverage and capacity requirements, identifying this as a critical step for a successful deployment. (Module: "WLAN Design and Configuration").

RSSI is an acronym for Received Signal Strength Indicator. It is a measurement of the power level that a wireless client is receiving from an access point. This value is not an absolute unit like milliwatts (mW) or decibel-milliwatts (dBm) but is a relative index used by the radio chipset. Wireless devices use RSSI to assess the quality of a connection and to determine when it is necessary to roam to another access point with a better signal. In the Juniper Mist platform, the "Coverage" Service Level Expectation (SLE) is directly measured using client RSSI values.

A. Frequency is the rate of oscillation of a radio wave, measured in Hertz (Hz), and is not a measure of signal power.

C. Interference is unwanted radio frequency energy from other sources that can degrade a signal, but RSSI does not specifically isolate and measure it.

D. Noise refers to the background radio frequency energy (noise floor); RSSI measures the power of the desired signal, which is distinct from the noise floor.

1. Juniper Mist Documentation, Wi-Fi Assurance: In the section describing Service Level Expectations (SLEs), the "Coverage" metric is defined. It states, "The Coverage SLE measures the mobile clients’ ability to hear the APs at a sufficient signal strength. We measure this by looking at the client’s RSSI..." This directly links RSSI to the measurement of signal strength.

Source: Juniper Networks, "Wi-Fi Assurance," Service Level Expectations (SLEs) section.

2. Juniper Networks Technical Documentation, Radio Resource Management (RRM): The documentation for RRM explains how coverage holes are detected. It states, "The RRM feature detects coverage holes by monitoring the RSSI values of clients. If a client's RSSI drops below a configured threshold... the RRM feature identifies a coverage hole." This confirms RSSI is the metric for signal strength monitoring.

Source: Juniper Networks TechLibrary, "Radio Resource Management," Coverage Hole Detection section.

3. Peer-Reviewed Academic Publication: A study on wireless localization techniques defines RSSI as a fundamental concept. "RSSI is a measurement of the power present in a received radio signal... It is often used in wireless sensor networks for localization and distance estimation."

Source: Zafari, F., Gkelias, A., & Leung, K. K. (2019). A Survey of Indoor Localization Systems and Technologies. IEEE Communications Surveys & Tutorials, 21(3), 2568-2599. Section III-A, "Fingerprinting." DOI: https://doi.org/10.1109/COMST.2019.2911558