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HCIA-IoT practice questions

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Question 1IoT Overview and Architecture

In the Huawei IoT reference architecture, which layer is responsible for sensing physical parameters and converting them into digital signals?

  1. The network layer
  2. The platform layer
  3. The application layer
  4. The perception layer Correct answer.

Explanation

The perception layer sits closest to the physical world and contains sensors, actuators, and edge devices that capture physical quantities and convert them into digital data. The other layers handle transport, data management, and business logic rather than direct sensing.

Question 2IoT Overview and Architecture

Which characteristic most distinguishes an IoT end device from a conventional desktop computer?

  1. It always runs a full desktop operating system
  2. It requires a wired Ethernet connection to function
  3. It is typically resource-constrained and optimized for a narrow sensing task Correct answer.
  4. It relies on a battery or energy harvesting

Explanation

IoT end devices are usually constrained in CPU, memory, and power, and are dedicated to a specific sensing or control function. That narrow, resource-limited design is the defining contrast with general-purpose computers.

Question 3IoT Overview and Architecture

A parking garage wants each parking space to report occupancy to a gateway several hundred meters away, using small battery-powered sensors that must last years. Which connectivity class best fits this requirement?

  1. HDMI
  2. Fibre Channel
  3. LPWA technologies such as NB-IoT Correct answer.
  4. Gigabit Ethernet

Explanation

Low-power wide-area technologies are designed for long range, low data rate, and multi-year battery life, which matches sparse occupancy reporting from small sensors. The other options are wired or short-range interfaces unsuited to dispersed battery-powered nodes.

Question 4IoT Overview and Architecture

What is the primary role of an IoT platform such as Huawei IoTDA?

  1. To define the physical layer modulation scheme
  2. To provide device management, data collection, and northbound APIs for applications Correct answer.
  3. To replace the radio access network
  4. To manufacture the physical sensors

Explanation

An IoT platform sits between devices and applications, handling device onboarding, connectivity management, data ingestion, and exposure of APIs to upper-layer applications. It does not manufacture hardware, replace radio access, or define modulation.

Question 5IoT Overview and Architecture

Which term describes the edge computing pattern in which data processing occurs close to the sensors rather than only in a distant cloud data center?

  1. Screen scraping
  2. Mainframe batch processing
  3. Data warehousing
  4. Edge computing Correct answer.

Explanation

Edge computing moves computation and storage nearer to the data source, reducing latency and backhaul load. The other terms describe unrelated legacy or data-processing practices.

Question 6IoT Overview and Architecture

Which statement correctly describes the relationship between IoT and M2M?

  1. IoT is a subset of M2M limited to sensor networks
  2. M2M is a subset concept focused on machine-to-machine communication, while IoT is broader and includes cloud, analytics, and applications Correct answer.
  3. M2M refers only to mobile phone messaging
  4. M2M and IoT are identical terms with no distinction

Explanation

M2M emphasizes direct communication between machines, often point-to-point and vertical. IoT extends this with IP networking, cloud platforms, data analytics, and application services, making it the broader concept.

Question 7IoT Overview and Architecture

Which of the following is a typical benefit cited for adopting IoT in industrial operations?

  1. Elimination of the need for any network infrastructure
  2. Removal of the need for security controls
  3. Guaranteed zero downtime for all machinery
  4. Predictive maintenance based on continuous equipment telemetry Correct answer.

Explanation

Continuous telemetry from equipment enables condition monitoring and predictive maintenance, reducing unplanned outages. IoT does not remove infrastructure or security needs, nor can it guarantee zero downtime.

Question 8IoT Overview and Architecture

Which component converts an analog sensor voltage into a digital value that a microcontroller can process?

  1. A power amplifier
  2. A diplexer
  3. An analog-to-digital converter Correct answer.
  4. A voltage regulator

Explanation

An analog-to-digital converter samples an analog signal and produces a discrete numeric value usable by a processor. The other components handle amplification, signal routing, or supply regulation.

Question 9IoT Overview and Architecture

A company deploys temperature sensors in a remote oil field with no terrestrial network coverage and needs low data volume at low cost. Which access technology is most appropriate?

  1. Infrared line-of-sight links
  2. Near Field Communication
  3. Bluetooth Low Energy
  4. Satellite IoT connectivity Correct answer.

Explanation

Satellite connectivity provides coverage in remote areas beyond terrestrial networks, and low-volume telemetry suits its cost profile. BLE, NFC, and infrared are short-range technologies unsuitable for isolated wide-area sites.

Question 10IoT Overview and Architecture

In a layered IoT architecture, which function belongs to the network layer rather than the platform layer?

  1. Exposing RESTful APIs to business applications
  2. Managing device lifecycles and firmware versions
  3. Forwarding device data through gateways and access networks to the cloud Correct answer.
  4. Storing time-series data for historical queries

Explanation

The network layer is responsible for transporting data from devices through gateways and access networks to higher layers. Storage, API exposure, and lifecycle management are platform-layer capabilities.

Question 11IoT Overview and Architecture

Why is a gateway often deployed between constrained sensor nodes and the cloud?

  1. To increase the physical range of each sensor's radio
  2. To replace the need for any security on the devices
  3. To aggregate and protocol-convert local device traffic before wide-area transmission Correct answer.
  4. To store the entire enterprise data lake locally

Explanation

Gateways collect data from local nodes, translate between protocols such as Zigbee and IP, and reduce backhaul traffic. They do not extend radio range arbitrarily, remove security needs, or act as an enterprise data lake.

Question 12IoT Overview and Architecture

Which pairing of IoT communication pattern and example is correct?

  1. Device-to-device only: a sensor publishing to a cloud dashboard
  2. Northbound control: a sensor reading a local bus register
  3. Device-to-cloud telemetry: a sensor publishing readings to an IoT platform over MQTT Correct answer.
  4. Southbound telemetry: an application querying a business database

Explanation

Publishing sensor readings to a platform over MQTT is the canonical device-to-cloud telemetry pattern. The other pairings mislabel the direction or the participants of the communication.

Question 13IoT Overview and Architecture

What is the main architectural reason to place analytics at the edge in a factory with high-frequency vibration data?

  1. To reduce backhaul bandwidth and latency by processing data near the machines Correct answer.
  2. To increase the physical size of the data center
  3. To eliminate the need for any cloud services permanently
  4. To avoid using sensors altogether

Explanation

High-frequency data would overwhelm backhaul if fully uploaded, so local processing filters and summarizes it before transmission, cutting bandwidth and latency. Edge analytics complements rather than permanently replaces cloud services.

Question 14IoT Overview and Architecture

Which statement about the application layer of an IoT architecture is accurate?

  1. It consumes platform APIs to deliver domain-specific services such as smart metering or fleet tracking Correct answer.
  2. It converts analog sensor voltages into digital values
  3. It directly modulates the radio signal sent by sensors
  4. It assigns IP addresses to end devices

Explanation

The application layer builds vertical services on top of platform APIs, delivering value such as metering or fleet tracking. Radio modulation, IP addressing, and analog conversion occur at lower layers.

Question 15IoT Overview and Architecture

A utility wants to read electricity meters once per hour with small payloads and needs deep indoor penetration. Which technology characteristic matters most?

  1. Support for uncompressed 4K video
  2. Strong link budget and low-power wide-area coverage Correct answer.
  3. Very high peak throughput
  4. Ultra-low latency below one millisecond

Explanation

Hourly meter reads need only small payloads, so coverage and penetration into basements dominate the choice, favoring LPWA technologies with strong link budgets. High throughput, ultra-low latency, and video support are irrelevant to this workload.

Question 16IoT Overview and Architecture

Which of the following best describes the role of device shadowing in an IoT platform?

  1. Assigning radio channels to devices
  2. Maintaining a virtual representation of device state so applications can read and command devices asynchronously Correct answer.
  3. Encrypting all traffic between devices and the platform
  4. Compiling firmware for microcontrollers

Explanation

A device shadow stores the last reported and desired state of a device, letting applications interact with it even when it is offline. Encryption, channel assignment, and firmware compilation are separate concerns.

Question 17IoT Overview and Architecture

Which set of elements is required for a basic end-to-end IoT solution?

  1. Only a mobile app and a web server
  2. Sensing devices, a connectivity network, a platform for data handling, and an application Correct answer.
  3. Only sensors and a database
  4. Only a gateway and a spreadsheet

Explanation

A complete IoT solution spans the perception, network, platform, and application layers so that data can be captured, transported, managed, and turned into services. The other sets omit essential layers.

Question 18IoT Overview and Architecture

A hospital needs to track infusion pumps indoors with room-level accuracy and very low tag cost. Which technology is most suitable?

  1. Cellular macro-cell positioning
  2. Long-range HF radio
  3. Satellite positioning
  4. BLE-based indoor positioning Correct answer.

Explanation

BLE beacons and tags provide low-cost indoor positioning at room-level granularity. Satellite, HF radio, and macro-cell positioning are unsuitable for accurate indoor localization.

Question 19IoT Overview and Architecture

Which statement correctly distinguishes narrowband IoT from broadband cellular service?

  1. Narrowband IoT prioritizes low power and wide coverage for small payloads rather than high data rates Correct answer.
  2. Narrowband IoT is limited to wired connections
  3. Narrowband IoT requires a full smartphone operating system
  4. Narrowband IoT provides higher throughput than broadband cellular

Explanation

Narrowband IoT is optimized for low-power, wide-coverage, small-payload machine communication, trading throughput for battery life and penetration. It is neither higher-throughput nor wired nor dependent on a smartphone OS.

Question 20IoT Overview and Architecture

What does the term southbound interface refer to in an IoT platform architecture?

  1. The billing interface to a telecom operator
  2. A physical port on the server chassis
  3. The interface used by business applications to consume platform services
  4. The interface through which the platform connects to and manages devices and gateways Correct answer.

Explanation

Southbound interfaces face the device side, handling device connectivity and management, while northbound interfaces face applications. The term is logical, not a chassis port or billing link.

Question 21IoT Overview and Architecture

An engineer must choose between a mesh short-range protocol and a cellular LPWA link for 5,000 streetlights spread across a city. Which consideration most strongly favors cellular LPWA?

  1. The need for guaranteed high-definition video streaming
  2. Lower cost of each individual radio module
  3. Wide-area coverage without building a multi-hop mesh across the city Correct answer.
  4. The requirement to avoid any subscription or SIM management

Explanation

Cellular LPWA provides operator-managed wide-area coverage, avoiding the complexity of deploying and maintaining a city-wide mesh. Module cost, video streaming, and SIM avoidance do not favor LPWA here.

Question 22IoT Overview and Architecture

Which design decision best reflects the principle that data should be processed at the tier where it delivers the most value?

  1. Disabling the network layer to reduce complexity
  2. Filtering high-rate sensor streams at the edge and sending only aggregated results to the cloud Correct answer.
  3. Sending every raw sample to the cloud regardless of volume
  4. Storing all data only on the sensor node with no upload

Explanation

Tiered processing assigns high-volume filtering to the edge and aggregation and analytics to the cloud, balancing bandwidth, latency, and cost. Uploading everything or storing only on nodes ignores the strengths of each tier.

Question 23IoT Overview and Architecture

In the Huawei IoT architecture, how do device management and connectivity management typically divide responsibilities?

  1. Connectivity management compiles firmware, while device management assigns radio frequencies
  2. Connectivity management handles SIM and network access, while device management handles registration, lifecycle, and firmware Correct answer.
  3. Connectivity management stores business reports, while device management renders dashboards
  4. Connectivity management performs analog conversion, while device management performs encryption

Explanation

Connectivity management concerns the network subscription and access state of devices, whereas device management covers registration, lifecycle state, and firmware operations. The other pairings assign unrelated functions to each area.

Question 24IoT Overview and Architecture

A team observes that a battery-powered sensor network's lifetime is far shorter than modeled. Which architectural factor is the most plausible root cause?

  1. The application dashboard refreshes too frequently
  2. The cloud platform stores too many time-series records
  3. The radio stays in receive mode for long windows because the duty cycle and wake-up schedule are poorly designed Correct answer.
  4. The sensor's analog-to-digital converter has too many bits of resolution

Explanation

Radio activity usually dominates energy consumption in battery nodes, so long receive windows and poor duty cycling drain the battery quickly. ADC resolution, cloud storage, and dashboard refresh have negligible effect on node energy.

Question 25IoT Overview and Architecture

Which scenario best illustrates why an IoT platform must support both northbound and southbound interfaces?

  1. Both interfaces are used only for billing reconciliation
  2. Both interfaces are used only for firmware storage
  3. Devices connect inward through southbound interfaces while business applications consume data through northbound APIs Correct answer.
  4. Devices connect through northbound interfaces while applications use southbound APIs

Explanation

The platform mediates between the device domain and the application domain, so it needs southbound connectivity toward devices and northbound APIs toward applications. Reversing the directions or limiting them to storage or billing misrepresents their purpose.

Question 26IoT Overview and Architecture

In the widely used three-tier view of an IoT system, which tier is responsible for aggregating sensor readings, applying protocol conversion, and forwarding data toward the cloud?

  1. The network (gateway) tier, which bridges local device networks to wider networks Correct answer.
  2. The perception tier, which only performs physical measurement
  3. The device tier, where sensing and actuation hardware reside
  4. The application tier, where business logic and user-facing services run

Explanation

The network or gateway tier sits between local device networks and the wider network, so it aggregates data, converts between protocols such as Modbus and MQTT, and forwards traffic upward. It does not host business logic, and it is not the layer where physical sensing occurs.

Question 27IoT Overview and Architecture

Which statement best explains why an IoT solution separates the device domain from the platform domain?

  1. It removes the need for any network connectivity between devices and applications
  2. It lets devices and applications evolve independently as long as the exposed interfaces stay stable Correct answer.
  3. It ensures devices always use the same hardware vendor as the platform
  4. It guarantees that all sensor data can be stored permanently on the device

Explanation

Decoupling devices from the platform means either side can be upgraded, replaced, or scaled without forcing changes on the other, provided the northbound and southbound interfaces remain compatible. This is the main reason layered IoT reference architectures draw a clear boundary between the two domains.

Question 28IoT Overview and Architecture

A building operator wants to add a new vibration-analytics application to an existing IoT deployment without changing the installed sensors or the connectivity layer. Which architectural characteristic makes this possible?

  1. Vertical integration, where each application owns its own dedicated sensor network
  2. Direct device-to-device messaging that bypasses the platform entirely
  3. Open northbound APIs exposed by the platform to application developers Correct answer.
  4. Manual export of raw sensor logs for offline processing

Explanation

A platform that exposes open northbound APIs lets new applications consume device data and invoke services without touching the sensor or connectivity layers. This is the practical payoff of horizontal layering in IoT architecture.

Question 29IoT Overview and Architecture

An architecture team is comparing a cloud-centric design with an edge-assisted design for a video surveillance service. Which consideration most directly favors placing inference at the edge?

  1. Edge inference increases the volume of raw video that must be uploaded
  2. Edge inference reduces backhaul bandwidth consumption and end-to-end response latency Correct answer.
  3. Edge inference removes the requirement for power and cooling at the edge site
  4. Edge inference eliminates the need for any device management function

Explanation

Running inference near the camera means only events or metadata need to be transmitted, which cuts backhaul usage and shortens response time compared with sending every frame to a distant data center. The trade-off is that edge nodes still need management, power, and cooling.

Question 30IoT Overview and Architecture

A system integrator must connect thousands of legacy meters that speak only a serial fieldbus to a cloud IoT platform. Which architectural placement of the protocol adaptation function is most appropriate, and why?

  1. At an on-site gateway, because it terminates the fieldbus locally and translates to an IP-based protocol toward the platform Correct answer.
  2. At the application server, because applications should interpret raw fieldbus frames directly
  3. At the meter, because every legacy meter can be reflashed to speak MQTT natively
  4. Inside the cloud platform, because fieldbus frames can be tunneled unchanged over the internet

Explanation

Legacy fieldbus devices usually cannot speak IP protocols, so a local gateway terminates the fieldbus, normalizes the data, and translates it into a platform-friendly protocol such as MQTT over IP. This keeps the adaptation close to the constrained devices and hides their specifics from the cloud.

Question 31IoT Communication Technologies

In the NB-IoT air interface, which uplink transmission scheme is used by the physical uplink shared channel (NPUSCH)?

  1. SC-FDMA with a single subcarrier or multiple subcarriers, using 15 kHz or 3.75 kHz spacing Correct answer.
  2. OFDMA with 15 kHz spacing and a 20 MHz channel
  3. OFDM with 60 kHz spacing and 24 subcarriers
  4. CDMA with a fixed 1.25 MHz spreading bandwidth

Explanation

NB-IoT uplink uses SC-FDMA on NPUSCH, and the subcarrier spacing can be either 15 kHz or 3.75 kHz. The 3.75 kHz option is used for coverage-enhanced single-tone transmission. Wider LTE-style channel bandwidths and CDMA spreading are not part of the NB-IoT uplink design.

Question 32IoT Communication Technologies

Which statement correctly describes the bandwidth occupied by an NB-IoT carrier?

  1. It occupies 20 MHz when deployed in the standalone mode
  2. It always occupies 1.4 MHz to match the smallest LTE channel
  3. It occupies 200 kHz only when deployed in-band
  4. It occupies one LTE resource block of 180 kHz regardless of deployment mode Correct answer.

Explanation

An NB-IoT carrier is designed around a single LTE physical resource block, which is 180 kHz wide. This holds for in-band, guard-band, and standalone operation. The narrow bandwidth is what enables low-cost devices and deep coverage extension.

Question 33IoT Communication Technologies

A utility company needs meters that run for many years on a small battery and send only a few hundred bytes per day. Which cellular IoT technology is designed specifically for this profile?

  1. NB-IoT Correct answer.
  2. 5G NR mmWave
  3. LTE-Advanced Pro carrier aggregation
  4. GSM circuit-switched data

Explanation

NB-IoT was standardized for low-power wide-area machine communication with extended coverage, low data rates, and long battery life. Its power-saving mode and extended discontinuous reception let devices sleep for long periods. High-throughput cellular features and mmWave are aimed at very different requirements.

Question 34IoT Communication Technologies

What is the primary role of the PSM (Power Saving Mode) feature in NB-IoT devices?

  1. The device stays registered but sleeps for long periods, waking only for periodic tracking area updates or uplink Correct answer.
  2. The device deregisters from the network each time it becomes idle
  3. The device reduces its transmit power to the minimum allowed level
  4. The device switches to a 3.75 kHz subcarrier spacing to save energy

Explanation

With PSM the device remains attached to the network but enters a deep sleep state, so it does not need to re-register on each wake-up. It wakes for periodic tracking area updates or when it has data to send. This avoids the signaling cost of repeated attach procedures and extends battery life.

Question 35IoT Communication Technologies

Which IoT wireless technology uses a chirp spread spectrum modulation and operates in unlicensed ISM bands with a typical range of several kilometers?

  1. LoRa Correct answer.
  2. Zigbee
  3. NFC
  4. Bluetooth Low Energy

Explanation

LoRa uses chirp spread spectrum modulation in unlicensed sub-GHz ISM bands, giving long range at low data rates. Its spreading factors allow a trade-off between range, data rate, and airtime. The other options are short-range technologies with different modulation schemes.

Question 36IoT Communication Technologies

In LoRaWAN, which device class keeps its receive window open continuously except while transmitting, allowing downlink at any time?

  1. Class C Correct answer.
  2. Class A
  3. Class B
  4. Class D

Explanation

Class C devices listen almost continuously and therefore have the lowest downlink latency but the highest power consumption. Class A opens two short receive windows after each uplink, and Class B adds scheduled ping slots. No Class D exists in the LoRaWAN specification.

Question 37IoT Communication Technologies

Which protocol is a lightweight publish/subscribe messaging protocol widely used in IoT platforms and typically runs over TCP port 1883?

  1. Modbus RTU
  2. SNMP
  3. CoAP
  4. MQTT Correct answer.

Explanation

MQTT is a broker-based publish/subscribe protocol that runs over TCP, with 1883 as its default plaintext port. Its small fixed header and topic-based routing suit constrained devices and unreliable links. CoAP is request/response over UDP, while Modbus RTU and SNMP serve other purposes.

Question 38IoT Communication Technologies

Which addressing and transport combination does CoAP use by default?

  1. UDP with a 16-byte header and no URI support
  2. TCP with TLS and a publish/subscribe broker
  3. TCP with a 2-byte length prefix and binary topic names
  4. UDP with a 4-byte fixed header and resource paths modeled as URIs Correct answer.

Explanation

CoAP is designed for constrained nodes and networks and runs over UDP, with a compact 4-byte fixed header. Resources are identified by URIs and accessed with methods such as GET, PUT, and POST. Reliability is provided optionally through confirmable messages rather than by TCP.

Question 39IoT Communication Technologies

A field device must send a small alarm message to a CoAP server and be certain the message was received. Which CoAP message type should the device use?

  1. Piggybacked empty ACK
  2. Reset (RST)
  3. Non-confirmable (NON)
  4. Confirmable (CON) Correct answer.

Explanation

A confirmable message requires the receiver to reply with an acknowledgement, so the sender can retransmit if none arrives. Non-confirmable messages are fire-and-forget and offer no delivery guarantee. RST and empty ACK are response codes rather than a choice of request reliability.

Question 40IoT Communication Technologies

What does the MQTT Quality of Service level 2 guarantee?

  1. Exactly-once delivery through a four-step handshake between publisher and broker Correct answer.
  2. At-most-once delivery with no retransmission
  3. At-least-once delivery with possible duplicates
  4. Ordered delivery only when using retained messages

Explanation

QoS 2 uses a PUBLISH, PUBREC, PUBREL, PUBCOMP exchange so that the message is delivered exactly once. QoS 0 gives at-most-once delivery and QoS 1 gives at-least-once delivery with possible duplicates. Retained messages affect how new subscribers receive the last value, not the delivery guarantee.

Question 41IoT Communication Technologies

An MQTT client connects with a will message configured. Under what condition does the broker publish that will message?

  1. Only when the client's subscription list becomes empty
  2. When the client's connection closes unexpectedly without a clean disconnect Correct answer.
  3. When the broker restarts and reloads its retained messages
  4. Every time the client disconnects, including a normal DISCONNECT packet

Explanation

The will message is stored at connect time and is published by the broker when the connection terminates abnormally, for example due to a network failure or keepalive timeout. A clean disconnect with a DISCONNECT packet suppresses the will. This makes the will useful for offline or fault notifications.

Question 42IoT Communication Technologies

Which mechanism lets a constrained device using 6LoWPAN send IPv6 packets over an IEEE 802.15.4 link?

  1. Header compression that elides fields shared with the link-layer addressing Correct answer.
  2. Encapsulating IPv6 inside TCP segments
  3. Translating IPv6 to Modbus at the gateway
  4. Using 128-bit MAC addresses instead of IPv6 addresses

Explanation

IEEE 802.15.4 frames are far too small for a full IPv6 header, so 6LoWPAN applies header compression and fragmentation. Fields that can be derived from link-layer information, such as interface identifiers, are elided. This keeps the overhead low enough for constrained links.

Question 43IoT Communication Technologies

In a LoRaWAN network, which entity is responsible for deduplicating uplink frames received by multiple gateways and for selecting the gateway used for downlink?

  1. The network server Correct answer.
  2. The application server
  3. The join server
  4. The end device

Explanation

Gateways forward received frames to the network server, which removes duplicates and decides which gateway should carry any downlink. The application server handles payload logic and the join server manages key derivation during activation. End devices do not perform this coordination.

Question 44IoT Communication Technologies

Which LoRaWAN activation method lets a device join the network without a per-device join procedure, using keys that are pre-provisioned by the manufacturer?

  1. Over-the-air activation (OTAA)
  2. Confirmed downlink join
  3. Class B beacon join
  4. Activation by personalization (ABP) Correct answer.

Explanation

ABP provisions the device address and session keys in advance, so the device can transmit immediately without a join exchange. OTAA performs a join request and accept exchange to derive fresh session keys. ABP is simpler but does not renew session keys on each join.

Question 45IoT Communication Technologies

What is the main purpose of the extended discontinuous reception (eDRX) feature in cellular IoT?

  1. To let a device remain reachable while sleeping in long cycles, reducing paging monitoring and power use Correct answer.
  2. To increase the peak uplink data rate for bursty traffic
  3. To encrypt the air interface between device and base station
  4. To allow the device to roam between different operators

Explanation

eDRX extends the paging cycle so the device wakes only at long intervals to check for pages, which saves energy while keeping downlink reachability. It is a compromise between continuous listening and the deeper sleep of PSM. Throughput, encryption, and roaming are separate concerns.

Question 46IoT Communication Technologies

A device using NB-IoT is deployed in a basement where signal attenuation is about 20 dB greater than normal LTE coverage. Which NB-IoT capability addresses this?

  1. Dual connectivity with a 5G NR link
  2. Higher-order 256-QAM modulation
  3. Carrier aggregation across multiple 180 kHz carriers
  4. Coverage enhancement through repetition of transmissions across many subframes Correct answer.

Explanation

NB-IoT provides coverage extension by repeating transmissions, which lets the receiver accumulate energy over many subframes. This trades data rate and latency for link budget. Higher-order modulation and carrier aggregation would make the link harder to close, not easier.

Question 47IoT Communication Technologies

Which statement best describes the relationship between LoRa and LoRaWAN?

  1. They are two names for the same specification maintained by the same body
  2. LoRaWAN is a transport-layer protocol that runs over LoRa only on TCP/IP networks
  3. LoRa is the physical-layer modulation, while LoRaWAN defines the network protocol and architecture above it Correct answer.
  4. LoRa is the network protocol, while LoRaWAN defines only the radio modulation

Explanation

LoRa defines the chirp spread spectrum physical layer, and LoRaWAN builds the MAC layer, device classes, and network architecture on top of it. A LoRa radio link can exist without LoRaWAN, and LoRaWAN depends on LoRa modulation. Confusing the two layers is a common source of error.

Question 48IoT Communication Technologies

Which addressing mode allows an MQTT client to subscribe to a hierarchical set of topics such as building/floor1/room2 using a single filter?

  1. Shared subscription with a $share prefix
  2. QoS 2 subscription with a session expiry
  3. Wildcard subscription with + and # characters Correct answer.
  4. Retained subscription with a zero-byte payload

Explanation

MQTT topic filters support the single-level wildcard + and the multi-level wildcard #, so one subscription can match many topics. For example, building/+/temperature matches every floor while building/# matches all descendants. Shared subscriptions distribute load but do not provide hierarchical matching.

Question 49IoT Communication Technologies

A sensor network uses IEEE 802.15.4 in beacon-enabled mode. What is the function of the superframe structure defined by the coordinator?

  1. It divides time into a beacon interval with a contention access period and an optional contention-free period using guaranteed time slots Correct answer.
  2. It assigns each node a permanent 16-bit address at manufacture
  3. It encrypts all frames with a network-wide key
  4. It increases the transmit power of end devices during the active period

Explanation

In beacon-enabled 802.15.4 the coordinator transmits beacons that bound a superframe, which contains a contention access period using CSMA/CA and may include a contention-free period of guaranteed time slots. This gives deterministic latency for selected traffic. Addressing, security, and power control are handled by other mechanisms.

Question 50IoT Communication Technologies

Which combination correctly pairs an IoT protocol with its native transport and interaction model?

  1. AMQP: TCP with a message-oriented publish/consume model using exchanges and queues Correct answer.
  2. MQTT: UDP with a request/response model
  3. CoAP: TCP with a publish/subscribe broker model
  4. LoRaWAN: TCP with a client/server model

Explanation

AMQP is a message-oriented protocol that runs over TCP and uses brokers with exchanges and queues to route messages. MQTT is publish/subscribe over TCP, CoAP is request/response over UDP, and LoRaWAN defines its own MAC layer rather than using TCP. Matching the transport and model correctly is essential.