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HCIP-IoT study materials
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HCIP-IoT practice questions

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Question 1IoT Overview and Architecture

In the standard three-layer IoT reference architecture, which layer is responsible for transmitting sensor data from the sensing layer to the network layer's edge and upward?

  1. The network layer Correct answer.
  2. The application layer
  3. The business/management layer
  4. The perception (sensing) layer

Explanation

The three-layer IoT reference model separates sensing (perception), network (transport), and application concerns. The network layer carries data collected by sensors across access and transport networks to platforms and applications. Sensing is where data is generated, and the application layer consumes the data.

Question 2IoT Overview and Architecture

Which characteristic most fundamentally distinguishes IoT devices from traditional Internet hosts such as desktop computers?

  1. IoT devices always use IPv6 while desktops use IPv4
  2. IoT devices never communicate over wireless links
  3. IoT devices are typically resource-constrained and often unattended in the field Correct answer.
  4. IoT devices always run full Linux distributions

Explanation

IoT endpoints are usually constrained in CPU, memory, energy, and are deployed unattended, which drives lightweight protocols and remote management. Traditional hosts have abundant resources and human operators. This constraint profile is the defining design difference.

Question 3IoT Overview and Architecture

A smart-meter deployment needs low power consumption, deep indoor coverage, and small infrequent uplink payloads, with devices expected to run for years on a battery. Which access technology best fits these requirements?

  1. Wi-Fi 6
  2. Ethernet
  3. NB-IoT Correct answer.
  4. Bluetooth Classic

Explanation

NB-IoT is an LPWA cellular technology designed for low power, deep coverage, and small infrequent messages, matching battery-powered meters. Ethernet requires wiring, Wi-Fi 6 is relatively power-hungry with limited range, and Bluetooth Classic is short-range and not suited to wide-area metering.

Question 4IoT Overview and Architecture

Which protocol is a lightweight publish/subscribe messaging protocol commonly used between constrained IoT devices and a broker?

  1. FTP
  2. MQTT Correct answer.
  3. RADIUS
  4. SNMP

Explanation

MQTT uses a broker-based publish/subscribe model with small headers and topic-based routing, making it suitable for constrained devices and unreliable links. SNMP is for device management, FTP for file transfer, and RADIUS for authentication and accounting.

Question 5IoT Overview and Architecture

An IoT solution architect wants a RESTful interface for constrained devices that supports a compact binary representation and uses UDP with optional reliability. Which protocol matches this description?

  1. HTTP/1.1 over TCP
  2. AMQP 1.0 over TCP
  3. DDS
  4. CoAP Correct answer.

Explanation

CoAP is a REST-style protocol designed for constrained nodes, running over UDP with optional confirmable messages for reliability and supporting compact binary options. HTTP/1.1 and AMQP run over TCP and are heavier, while DDS is a data-centric publish/subscribe middleware rather than a RESTful request/response protocol.

Question 6IoT Overview and Architecture

Which statement correctly describes the role of an IoT platform in the reference architecture?

  1. It only stores raw sensor readings without any device management
  2. It aggregates device data, manages devices, and exposes APIs to applications Correct answer.
  3. It replaces the need for any device connectivity protocol
  4. It is limited to physical gateway hardware without software services

Explanation

An IoT platform sits between connectivity and applications, providing device management, data ingestion, storage, analytics, and open APIs. It does not eliminate connectivity protocols and is primarily a software service layer, not just hardware.

Question 7IoT Overview and Architecture

A factory deploys thousands of sensors that must send telemetry to a cloud platform with guaranteed message delivery, ordering, and support for multiple transport bindings. Which messaging standard is designed with these enterprise-grade features?

  1. AMQP Correct answer.
  2. MQTT
  3. LwM2M
  4. CoAP

Explanation

AMQP provides rich messaging semantics including reliability, flow control, and multiple transport bindings, suited to enterprise integration. MQTT is lighter with QoS levels but fewer enterprise features, CoAP targets constrained RESTful interaction, and LwM2M is a device management protocol.

Question 8IoT Overview and Architecture

In a typical IoT end-to-end architecture, what is the primary function of an edge gateway?

  1. To bridge local device networks to wide-area networks and perform protocol translation Correct answer.
  2. To provide only physical power to end devices
  3. To terminate all application business logic in the cloud
  4. To replace sensors by generating synthetic data

Explanation

Edge gateways aggregate data from local device networks such as Zigbee or Modbus and forward it over wide-area links, often translating protocols and performing local preprocessing. They do not replace cloud business logic, generate sensor data, or merely supply power.

Question 9IoT Overview and Architecture

Which technology is specifically standardized for lightweight device management of constrained IoT devices, providing object-based resources over CoAP?

  1. NETCONF
  2. LwM2M Correct answer.
  3. TR-069
  4. SNMPv3

Explanation

LwM2M defines a lightweight device management protocol using CoAP transport and a standardized object/resource model for constrained devices. TR-069 targets broadband customer premises equipment, NETCONF targets network devices over SSH, and SNMPv3 is a general management protocol not optimized for constrained nodes.

Question 10IoT Overview and Architecture

A company wants to reduce latency and bandwidth for a video-analytics IoT system by processing frames near the cameras. Which architectural approach does this describe?

  1. Pure cloud computing
  2. Edge computing Correct answer.
  3. Centralized mainframe processing
  4. Batch processing in a remote data center

Explanation

Edge computing places computation near the data source, reducing latency and backhaul bandwidth by processing locally. Pure cloud, mainframe, and remote batch processing all move data far from the source and increase latency.

Question 11IoT Overview and Architecture

Which security concern is most specific to IoT deployments compared with traditional IT systems?

  1. Password reuse on corporate laptops
  2. Phishing emails targeting office workers
  3. Firewall rule misconfiguration on servers
  4. Long-lived unattended devices with weak default credentials that are hard to patch Correct answer.

Explanation

IoT devices are often deployed unattended for years, ship with default credentials, and lack easy update mechanisms, creating a distinct risk profile. Phishing, firewall misconfiguration, and laptop password reuse are general IT concerns rather than IoT-specific.

Question 12IoT Overview and Architecture

In the oneM2M standard, which entity provides common service functions such as registration, discovery, and data management to applications?

  1. The Node Management Entity (NME)
  2. The Network Services Entity (NSE)
  3. The Application Entity (AE)
  4. The Common Services Entity (CSE) Correct answer.

Explanation

oneM2M defines the Common Services Entity as the layer providing shared service functions like registration, discovery, and data management. Application Entities are the applications themselves, while the other options are not the oneM2M entity that supplies common service functions.

Question 13IoT Overview and Architecture

Which IoT reference model organizes the system into perception, network, and application layers as its core structure?

  1. The TCP/IP four-layer model
  2. The Purdue enterprise reference model
  3. The OSI seven-layer model
  4. The three-layer IoT architecture model Correct answer.

Explanation

The three-layer IoT architecture model consists of perception, network, and application layers. The OSI and TCP/IP models describe general networking, and the Purdue model describes industrial control hierarchies.

Question 14IoT Overview and Architecture

A fleet of battery-powered environmental sensors must report every few hours through a cellular network with minimal signaling overhead and support for extended discontinuous reception. Which capability is most relevant?

  1. Voice over LTE
  2. Power Saving Mode (PSM) and eDRX in NB-IoT Correct answer.
  3. Carrier aggregation of multiple LTE bands
  4. eMBB high-throughput bearer

Explanation

NB-IoT provides Power Saving Mode and extended DRX to let devices sleep deeply and reduce signaling, which suits infrequent battery-powered reporting. eMBB, carrier aggregation, and VoLTE target high throughput or voice and do not address this low-power profile.

Question 15IoT Overview and Architecture

Which statement best explains why MQTT uses a broker rather than direct device-to-device connections?

  1. A broker guarantees real-time delivery within one millisecond
  2. A broker decouples publishers and subscribers, simplifying scaling and topic-based routing Correct answer.
  3. A broker eliminates the need for a transport protocol
  4. A broker encrypts all payloads so devices need no security

Explanation

The broker decouples publishers from subscribers, so devices do not need to know each other and topics can be routed and scaled centrally. The broker does not inherently encrypt payloads, guarantee one-millisecond latency, or remove the need for a transport protocol.

Question 16IoT Overview and Architecture

Which protocol is a lightweight, binary, publish/subscribe protocol often used in industrial IoT and SCADA environments?

  1. DDS Correct answer.
  2. BACnet
  3. OPC UA
  4. Modbus RTU

Explanation

DDS is a data-centric publish/subscribe middleware standard used in industrial and mission-critical IoT systems. OPC UA is a service-oriented industrial interoperability standard, Modbus RTU is a master-slave fieldbus, and BACnet targets building automation.

Question 17IoT Overview and Architecture

An architect must choose a network topology for a low-power sensor mesh in which nodes relay each other's traffic to extend range. Which topology does this describe?

  1. Point-to-point topology
  2. Mesh topology Correct answer.
  3. Bus topology
  4. Star topology

Explanation

In a mesh topology, nodes forward traffic for one another, extending coverage and adding path redundancy. Star relies on a central hub, point-to-point links only two endpoints, and bus shares a single backbone.

Question 18IoT Overview and Architecture

Which statement correctly describes the relationship between 5G network slicing and IoT use cases?

  1. A slice removes the need for any device authentication
  2. A slice only applies to voice services
  3. A slice is a physical SIM card assigned to one device
  4. A slice provides an isolated logical network with tailored latency, bandwidth, and reliability Correct answer.

Explanation

5G network slicing creates logically isolated network instances with service-specific performance characteristics, allowing eMBB, URLLC, and mMTC traffic to coexist. A slice is not a SIM, is not limited to voice, and does not remove authentication requirements.

Question 19IoT Overview and Architecture

Which IoT connectivity technology is best suited to short-range, low-power personal-area networks such as wearable health monitors?

  1. NB-IoT
  2. Bluetooth Low Energy Correct answer.
  3. LoRaWAN
  4. Sigfox

Explanation

Bluetooth Low Energy is designed for short-range, low-power personal-area links such as wearables. LoRaWAN, NB-IoT, and Sigfox are wide-area LPWA technologies intended for longer-range deployments.

Question 20IoT Overview and Architecture

A team must ensure that firmware updates pushed to thousands of field devices are authenticated and cannot be rolled back to a vulnerable version. Which combination of mechanisms best addresses this?

  1. Plain HTTP download with a filename checksum
  2. Broadcast of the update to all devices simultaneously
  3. Cryptographically signed firmware plus anti-rollback version counters in secure storage Correct answer.
  4. Compression of the firmware image to reduce size

Explanation

Signed firmware verifies authenticity and integrity, while anti-rollback counters stored securely prevent downgrade to known-vulnerable versions. Plain HTTP with a filename checksum, compression, and simultaneous broadcast do not provide these protections.

Question 21IoT Gateways and Device Connectivity

In an NB-IoT deployment, which network element terminates the control-plane signalling between the UE and the core network when Control Plane CIoT EPS optimisation is used?

  1. The S-GW, which decodes NAS messages before forwarding them to the P-GW
  2. The P-GW, which acts as the NAS anchor for all idle-mode UEs
  3. The HSS, which relays NAS messages to the UE over the S6a interface
  4. The MME, which carries NAS messages over S1-AP with the eNB transparently forwarding them Correct answer.

Explanation

With Control Plane CIoT EPS optimisation, user data is carried inside NAS PDUs, so the MME is the termination point for signalling and for the encapsulated small data. The eNB only relays these NAS messages inside S1-AP and does not interpret the payload. The S-GW and P-GW remain user-plane gateways and are not NAS endpoints.

Question 22IoT Gateways and Device Connectivity

A gateway must forward uplink CoAP messages from constrained devices to an HTTP-based cloud API. Which function should the gateway implement?

  1. A DHCP relay agent for the constrained devices
  2. A RADIUS accounting proxy for the devices
  3. An SNMP trap forwarder to the cloud API
  4. A CoAP-to-HTTP protocol translation proxy Correct answer.

Explanation

Protocol interworking between CoAP and HTTP requires an application-layer proxy that maps CoAP methods, options and response codes onto HTTP semantics. DHCP relay, SNMP forwarding and RADIUS accounting operate at different layers and cannot translate CoAP payloads into HTTP requests.

Question 23IoT Gateways and Device Connectivity

Which statement describes the role of the SCEF/NEF in a 3GPP cellular IoT architecture?

  1. It exposes network capabilities and service APIs to third-party application servers Correct answer.
  2. It allocates link-local IPv6 addresses to constrained devices
  3. It stores the device's firmware image for FOTA delivery
  4. It performs DTLS termination for CoAP traffic from devices

Explanation

The Service Capability Exposure Function, later generalised as the Network Exposure Function, provides a secure, standardised API through which external application servers can request network services such as monitoring, device triggering and non-IP data delivery. Address allocation, DTLS termination and firmware storage belong to other entities.

Question 24IoT Gateways and Device Connectivity

A device uses MQTT over TLS to a broker. Which combination correctly describes the default ports and the transport security layer used?

  1. Port 8883 with TLS and port 1883 without TLS Correct answer.
  2. Port 1883 with TLS and port 8883 without TLS
  3. Port 443 with TLS and port 80 without TLS
  4. Port 5683 with TLS and port 5684 without TLS

Explanation

MQTT conventionally uses TCP port 1883 for plaintext connections and port 8883 for connections protected by TLS. Ports 5683 and 5684 belong to CoAP over UDP, and 80/443 are HTTP ports rather than MQTT defaults.

Question 25IoT Gateways and Device Connectivity

An MQTT client connects with clean session set to false and a fixed client identifier. What behaviour does the broker provide?

  1. It stores the subscription and queues QoS 1 and QoS 2 messages for the client while it is offline Correct answer.
  2. It deletes the session state each time the client disconnects
  3. It downgrades all subscriptions to QoS 0 for the duration of the session
  4. It rejects the connection because persistent sessions require a random client identifier

Explanation

A persistent session, requested with clean session false in MQTT 3.1.1 or clean start false with a non-zero session expiry in MQTT 5, causes the broker to keep subscriptions and buffer matching QoS 1 and QoS 2 messages during disconnection. The client identifier must be stable so the broker can re-associate the session. QoS 0 messages are not stored for offline delivery.

Question 26IoT Gateways and Device Connectivity

Which mechanism allows an MQTT-SN client to receive messages without maintaining a permanent connection to the gateway?

  1. Sending a PUBLISH message with QoS 3
  2. Using the WILL message to poll the broker
  3. Registering a topic identifier and using the asleep state with buffered messages Correct answer.
  4. Relying on the gateway to broadcast all topics periodically

Explanation

MQTT-SN supports a sleep procedure in which the client registers topic identifiers, enters the asleep state, and the gateway buffers messages destined for it until the client wakes and sends a PINGREQ. This conserves energy for battery-powered sensor nodes. MQTT-SN defines QoS levels -1, 0, 1 and 2, but no QoS 3.

Question 27IoT Gateways and Device Connectivity

A constrained device must report temperature readings to a CoAP server and receive the value only when it changes. Which CoAP mechanism fits this requirement?

  1. An observe relationship registered with the server using the Observe option Correct answer.
  2. A confirmable GET repeated every second by the device
  3. A block-wise POST of the entire history each time
  4. A multicast GET sent to the all-nodes address

Explanation

The CoAP Observe extension (RFC 7641) lets a client register interest in a resource so the server pushes a notification whenever the representation changes. This avoids polling and reduces traffic. Repeated GETs and bulk POSTs waste energy and bandwidth, and multicast GET is unsuitable for per-device change notification.

Question 28IoT Gateways and Device Connectivity

In LoRaWAN, which entity is responsible for selecting the data rate and channel for each uplink through the ADR mechanism?

  1. The application server, which sets the data rate based on payload size
  2. The end device, which autonomously increases its data rate whenever battery voltage drops
  3. The join server, which assigns a fixed data rate during the join procedure
  4. The network server, which evaluates link quality and instructs the device via MAC commands Correct answer.

Explanation

Adaptive Data Rate in LoRaWAN is managed by the network server, which assesses uplink quality from received messages and sends LinkADRReq MAC commands to adjust data rate, transmit power and channel mask. The end device applies the commands rather than deciding autonomously. The join server handles key derivation, and the application server processes payloads.

Question 29IoT Gateways and Device Connectivity

Which LoRaWAN device class keeps its receiver open continuously except while transmitting, allowing downlink at any time?

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

Explanation

Class C devices keep the receive window open almost continuously, so the network can send downlinks at any time at the cost of higher power consumption. Class A opens two short receive windows after each uplink, and Class B adds scheduled ping slots. LoRaWAN does not define a Class D.

Question 30IoT Gateways and Device Connectivity

A gateway is configured to use MQTT bridging to an upstream broker. What is the effect on message flow between the local broker and the remote broker?

  1. The bridge converts MQTT messages into CoAP requests for the upstream server
  2. The bridge forwards messages according to topic filters and can set a different QoS on each direction Correct answer.
  3. The bridge replicates every retained message to all connected clients regardless of topic
  4. The bridge replaces the local broker and terminates all client sessions itself

Explanation

An MQTT bridge connects two brokers and forwards messages that match configured topic filters, with independently configurable QoS and direction for each filter. It does not replace the local broker, broadcast unrelated retained messages, or translate MQTT into CoAP.

Question 31IoT Gateways and Device Connectivity

Which statement about the Zigbee Coordinator in a Zigbee mesh network is accurate?

  1. It can only communicate with end devices through a direct point-to-point link
  2. It is always battery powered and sleeps between beacon intervals
  3. It must leave the network after formation to allow routers to take over
  4. It forms the network, selects the PAN identifier and channel, and can act as the trust centre Correct answer.

Explanation

The Zigbee Coordinator is responsible for forming the network, choosing the PAN ID and radio channel, and commonly hosts the trust centre that manages network keys. It is normally mains powered and remains part of the network. Routers extend coverage and end devices may sleep.

Question 32IoT Gateways and Device Connectivity

A BLE device uses a GATT characteristic to report a sensor value. Which attribute combination determines whether the client can read the value and receive notifications?

  1. The preferred connection parameters and the TX power level
  2. The characteristic properties field and the client characteristic configuration descriptor Correct answer.
  3. The device name and the appearance characteristic
  4. The advertising interval and the connection supervision timeout

Explanation

In GATT, the characteristic declaration contains a properties field that advertises supported operations such as read, write and notify. To enable notifications the client writes to the Client Characteristic Configuration Descriptor. Advertising and connection parameters affect link behaviour, not attribute permissions.

Question 33IoT Gateways and Device Connectivity

Which addressing mode does 6LoWPAN use to compress IPv6 headers when the link-layer addresses can be derived from the IPv6 addresses?

  1. Stateless address autoconfiguration with duplicate address detection
  2. Context-based compression with the context identifier extension
  3. Neighbour discovery with multicast solicitation
  4. Header compression using the LOWPAN_IPHC encoding Correct answer.

Explanation

6LoWPAN header compression is defined by the LOWPAN_IPHC encoding in RFC 6282, which elides fields when they can be inferred from link-layer addresses or shared context. Context-based compression is an extension for shared prefixes, not the base mechanism. Autoconfiguration and neighbour discovery are address management procedures, not header compression.

Question 34IoT Gateways and Device Connectivity

A deployment needs IPv6 connectivity for constrained nodes that only support 6LoWPAN over IEEE 802.15.4. Which gateway function is required at the boundary to the IPv6 Internet?

  1. A NAT44 translator that maps private IPv4 addresses to public ones
  2. A DNS64 server that rewrites AAAA records for the nodes
  3. A PPPoE server that assigns IPv4 addresses to the nodes
  4. A 6LoWPAN adaptation layer that compresses headers and performs fragmentation, plus an IPv6 router Correct answer.

Explanation

A 6LoWPAN edge router performs adaptation between IEEE 802.15.4 frames and IPv6, including header compression and fragmentation, and routes IPv6 packets to and from the wider network. NAT44, PPPoE and DNS64 do not provide 6LoWPAN adaptation for constrained nodes.

Question 35IoT Gateways and Device Connectivity

Which security mode in Zigbee uses a network key shared by all nodes plus per-device link keys for key transport?

  1. The standard security mode with a trust centre Correct answer.
  2. The residential mode without any key management
  3. The no-security mode with MAC frame protection disabled
  4. The green power mode with proxy authentication

Explanation

Zigbee standard security relies on a network key used for broadcast-level protection and link keys used between the trust centre and each device to deliver that network key securely. No-security mode provides no cryptographic protection, and green power is a energy-harvesting device feature, not a key management mode.

Question 36IoT Gateways and Device Connectivity

A device management platform uses LwM2M. Which interface does the LwM2M client use to register with the server and report its objects?

  1. The Information Reporting interface
  2. The Device Management and Service Enablement interface
  3. The Bootstrap interface
  4. The Registration interface Correct answer.

Explanation

The LwM2M Registration interface lets the client register with the server, providing its endpoint name and the object instances it supports. Bootstrap provisions credentials and server information, Device Management and Service Enablement carries read, write and execute operations, and Information Reporting handles notifications.

Question 37IoT Gateways and Device Connectivity

Which transport binding does LwM2M specify for constrained devices that cannot use UDP-based CoAP?

  1. CoAP over TCP with TLS Correct answer.
  2. MQTT with QoS 2 only
  3. HTTP with JSON only
  4. CoAP over SMS only

Explanation

LwM2M supports CoAP over UDP with DTLS and also defines a binding of CoAP over TCP secured with TLS for devices or networks where UDP is impractical. SMS and HTTP are not the LwM2M transport bindings, and MQTT is not part of the LwM2M specification.

Question 38IoT Gateways and Device Connectivity

A gateway performs store-and-forward for intermittently connected sensors. Which design choice best preserves message ordering per sensor?

  1. Drop messages whenever the uplink buffer exceeds one message
  2. Rely on the transport to reorder messages at the cloud
  3. Send all buffered messages in parallel over independent connections
  4. Assign each sensor a monotonically increasing sequence number and persist a per-sensor queue Correct answer.

Explanation

Per-sensor sequence numbers combined with a persistent queue let the gateway retransmit in order and let the cloud detect gaps or duplicates. Dropping on buffer pressure loses data, parallel connections do not guarantee ordering, and the transport cannot restore order that was never recorded.

Question 39IoT Gateways and Device Connectivity

Which mechanism does a cellular IoT module use to reduce power consumption by staying registered but not monitoring the paging channel continuously?

  1. NAS attach with a new IMSI allocation
  2. eDRX, which extends the paging cycle beyond the normal DRX cycle Correct answer.
  3. PDN connection deactivation and reactivation
  4. RRC connection release with redirection to another frequency

Explanation

Extended Discontinuous Reception lengthens the paging cycle so the UE wakes less often while remaining attached and reachable, trading latency for battery life. RRC redirection, IMSI reallocation and PDN deactivation do not provide the long paging cycle.

Question 40IoT Gateways and Device Connectivity

A device uses PSM. Which statement correctly describes its reachability?

  1. The device is reachable only through SMS during power saving mode
  2. The device is unreachable for mobile-terminated traffic during the active timer period
  3. The device remains reachable for paging during the extended periodic TAU timer Correct answer.
  4. The device must re-attach to the network after every sleep period

Explanation

With Power Saving Mode the UE negotiates an active timer and an extended periodic TAU timer. During the active timer it stays reachable; after that it sleeps and is not paged, but it remains registered and reachable again when it wakes for the periodic TAU. It does not need to re-attach after each sleep.

Question 41IoT Gateways and Device Connectivity

Which protocol is designed for constrained nodes and provides RESTful interaction over UDP with a small message overhead?

  1. SMTP
  2. HTTP/1.1
  3. CoAP Correct answer.
  4. FTP

Explanation

CoAP is a REST-style protocol built on UDP with compact binary headers and support for confirmable messages, making it suitable for constrained devices and lossy networks. HTTP/1.1, SMTP and FTP rely on TCP and carry larger headers.

Question 42IoT Gateways and Device Connectivity

A gateway must authenticate thousands of devices using certificates. Which practice best supports efficient certificate lifecycle management?

  1. Disabling certificate revocation checks to reduce gateway load
  2. Using self-signed certificates that never expire
  3. Issuing each device a unique certificate from a managed CA and rotating it before expiry Correct answer.
  4. Sharing one private key across all devices to simplify provisioning

Explanation

Unique per-device certificates issued by a managed certificate authority allow individual revocation and enable automated rotation before expiry. Shared keys remove device identity, disabled revocation checks allow compromised devices to remain trusted, and non-expiring self-signed certificates cannot be centrally managed.

Question 43IoT Gateways and Device Connectivity

In a Thread network, which role is responsible for assigning IPv6 addresses to devices that join the mesh?

  1. The Commissioner, which hands out addresses during commissioning
  2. The Router, which allocates addresses to its children only
  3. The Border Router, which provides connectivity to the wider IPv6 network Correct answer.
  4. The Leader, which assigns all on-mesh prefixes and addresses

Explanation

The Thread Border Router connects the mesh to an external IPv6 network and distributes the on-mesh prefix, enabling devices to form globally routable addresses. The Leader manages network data and router ID assignment, routers forward traffic, and the Commissioner authenticates joining devices.

Question 44IoT Gateways and Device Connectivity

A device sends CoAP confirmable requests but never receives acknowledgements. Which behaviour should the client implement according to the CoAP retransmission rules?

  1. Retransmit with an exponentially increasing timeout up to a maximum number of attempts, then report failure Correct answer.
  2. Switch to non-confirmable messages after the first timeout
  3. Immediately close the socket and re-register with the server
  4. Retransmit at a fixed interval indefinitely until an acknowledgement arrives

Explanation

CoAP confirmable messages use a retransmission timer that doubles after each timeout, starting from an initial randomised value, up to a maximum retransmit count; after that the message is considered failed. Fixed-interval infinite retransmission wastes energy and never terminates.

Question 45IoT Gateways and Device Connectivity

Which statement about the relationship between an IoT gateway and a device's local network is accurate?

  1. The gateway can perform edge processing and protocol conversion before forwarding data upstream Correct answer.
  2. The gateway must forward all raw data without any local processing
  3. The gateway must be located in the same physical enclosure as each device
  4. The gateway replaces the need for any device-level security configuration

Explanation

An IoT gateway commonly aggregates devices, performs local protocol conversion and edge analytics, and forwards only relevant data upstream. It does not have to forward raw data untouched, need not be co-located physically with devices, and does not remove the need for device-level security.

Question 46IoT Gateways and Device Connectivity

An IoT gateway aggregates telemetry from battery-powered sensors and forwards it to a cloud platform. Which gateway function is being performed when the gateway temporarily buffers sensor data while the WAN uplink is down and sends it after the link recovers?

  1. Protocol translation between CoAP and HTTP
  2. Local policy enforcement and access control
  3. Store-and-forward buffering Correct answer.
  4. Device authentication and key management

Explanation

Store-and-forward is a gateway function in which data received from devices is held in local storage during WAN outages and transmitted upstream once connectivity returns, preserving data that would otherwise be lost. The other listed functions describe different gateway roles that do not involve temporary retention of telemetry.

Question 47IoT Gateways and Device Connectivity

A gateway connects IEEE 802.15.4 sensor nodes to an IPv6 cloud backend. The nodes run 6LoWPAN and the gateway must act as the IPv6 router for the constrained link, answering Neighbor Discovery on their behalf. Which function must the gateway implement?

  1. CoAP observe server
  2. RPL root with non-storing mode only
  3. 6LoWPAN-ND proxy (Neighbor Discovery optimization) Correct answer.
  4. DTLS record-layer termination

Explanation

6LoWPAN Neighbor Discovery optimization lets a router such as the gateway act as a proxy that answers Neighbor Solicitation and related messages for constrained nodes, sparing them multicast and signaling overhead. This is the defined role of the 6LoWPAN-ND proxy at the edge router.

Question 48IoT Gateways and Device Connectivity

A cellular IoT module alternates between extended idle periods and short reporting bursts. The operator supports eDRX. What does enabling eDRX change about the module's behavior compared with normal idle mode?

  1. The module disables all downlink paging and relies solely on uplink polling.
  2. The module keeps its radio receiver continuously active to guarantee immediate downlink.
  3. The module listens for paging only during negotiated, extended paging occasions instead of every paging cycle. Correct answer.
  4. The module detaches from the network and re-attaches for each reporting burst.

Explanation

eDRX extends the paging cycle so the device only monitors paging channels at longer, negotiated intervals, reducing receiver-on time while remaining reachable. The device stays attached and registered; only the timing of paging monitoring changes.

Question 49IoT Gateways and Device Connectivity

A deployment uses BLE for short-range sensor links to a gateway. Which GATT role does the gateway take when it reads characteristic values from a sensor that exposes them?

  1. GATT client Correct answer.
  2. GATT server
  3. GAP broadcaster
  4. GAP peripheral

Explanation

In GATT, the side that initiates read and write procedures is the client, while the side holding the attribute database is the server. A gateway reading a sensor's characteristic values is therefore acting as the GATT client, regardless of which device is the GAP peripheral.

Question 50IoT Gateways and Device Connectivity

A gateway is deployed in a LoRaWAN network and must forward uplinks to the network server. Which statement correctly describes the gateway's role in LoRaWAN?

  1. It demodulates LoRa frames and forwards them to the network server without decrypting the payload or performing MAC-layer processing. Correct answer.
  2. It performs adaptive data rate decisions and schedules downlink windows for end devices.
  3. It terminates the LoRaWAN MAC layer and decrypts payloads before forwarding them to the application server.
  4. It assigns device addresses and session keys to end devices during join procedures.

Explanation

A LoRaWAN gateway is a transparent relay: it receives LoRa frames and forwards them over an IP backhaul to the network server, which handles MAC-layer processing, address management, and payload decryption. The gateway does not hold session keys or make scheduling decisions.