Through which messaging pattern does MQTT distribute data?
A Master/slave
B Publish/subscribe
C Request/response
D File transfer
Answer: B. Publish/subscribe. MQTT uses publish/subscribe messaging: publishers send to topics and subscribers receive matching messages.
Inside MQTT, which server routes messages between clients?
A Web page
B Broker
C Sensor node
D Registrar
Answer: B. Broker. The MQTT broker receives published messages and forwards them to clients with matching subscriptions.
For MQTT, what does a topic identify?
A Encryption key
B Network address
C Message subject
D Device serial
Answer: C. Message subject. A topic is a named message subject that clients publish to or subscribe to.
With MQTT QoS 0, what delivery level applies?
A At most once
B Two confirmations
C At least once
D Exactly once
Answer: A. At most once. QoS 0 sends without a delivery acknowledgment, so a message may be lost but is not retried by that QoS exchange.
Under MQTT QoS 1, what delivery level is guaranteed?
A Exactly once
B At most once
C At least once
D No delivery
Answer: C. At least once. QoS 1 provides at-least-once delivery, so a receiver can see a duplicate.
Which MQTT level targets exactly-once delivery?
A QoS 0
B QoS 1
C QoS 2
D QoS 3
Answer: C. QoS 2. MQTT QoS 2 uses a multi-step exchange for exactly-once protocol delivery.
CoAP was designed especially for what type of nodes?
A Desktop workstations
B Media servers
C High-end clusters
D Constrained nodes
Answer: D. Constrained nodes. CoAP targets constrained nodes and networks common in machine-to-machine and IoT systems.
Under RFC 7252, which transport carries base CoAP messages?
A FTP
B SCTP
C UDP
D SMTP
Answer: C. UDP. The original CoAP specification defines a binding over UDP; later standards also define other transports.
What interaction style is common for HTTP APIs?
A Token ring
B Publish/subscribe
C Circuit switching
D Request-response
Answer: D. Request-response. HTTP clients send requests and receive responses from servers.
Between a microcontroller and nearby peripherals, which bus is common?
A I2C bus
B UART bus
C SPI bus
D CAN bus
Answer: A. I2C bus. I2C is a short-distance serial bus commonly used to connect chips on the same board.
To carry IPv6 over IEEE 802.15.4, which adaptation is used?
A DNS-SD
B NAT64
C 6LoWPAN
D MIME
Answer: C. 6LoWPAN. 6LoWPAN adapts IPv6 for low-power IEEE 802.15.4 networks.
Bluetooth Low Energy is suited to which link profile?
A Satellite backbone
B High-power broadcast
C Long-haul fiber
D Short-range low-power
Answer: D. Short-range low-power. Bluetooth LE is designed for low-power wireless links, commonly over short distances.
LoRaWAN targets which network category?
A High-speed LAN
B Wired local bus
C Optical backbone
D Low-power wide-area
Answer: D. Low-power wide-area. LoRaWAN is a low-power wide-area networking protocol for battery-operated IoT devices.
Zigbee uses which underlying radio standard?
A IEEE 802.16
B IEEE 802.15.4
C IEEE 802.11
D IEEE 802.3
Answer: B. IEEE 802.15.4. Zigbee uses an IEEE 802.15.4 physical and MAC layer for its low-rate wireless networking.
On an IP network, what can DHCP assign to a client?
A MAC address
B Wi-Fi SSID
C TCP port
D IP address
Answer: D. IP address. DHCP can automatically provide IP configuration, including an IP address, to network clients.
At the network layer, how long is an IPv6 address?
A 128 bits
B 64 bits
C 48 bits
D 32 bits
Answer: A. 128 bits. IPv6 addresses are 128 bits long.
Using an RFID reader, how can a passive tag be identified?
A Laser beams
B Radio signals
C Copper wires
D Sound pulses
Answer: B. Radio signals. An RFID reader uses radio-frequency signals to communicate with and identify tags.
Across unlike networks, what can a gateway perform?
A Protocol translation
B Key guessing
C Image rendering
D Sensor calibration
Answer: A. Protocol translation. A gateway can translate between protocols used by local devices and an upstream network.
Which format commonly represents structured IoT data?
A JSON
B ZIP
C MP3
D JPEG
Answer: A. JSON. JSON is a widely used text format for structured data exchanged by applications.
When a new MQTT subscriber joins, what can provide the latest topic value?
A First sent value
B Last stored value
C All past values
D No prior value
Answer: B. Last stored value. A broker can store the latest retained message for a topic and send it to a new matching subscriber.
For ordinary web requests from a dashboard, which protocol is common?
A HTTP
B CoAP multicast
C I2C
D UART
Answer: A. HTTP. Web dashboards commonly use HTTP to request data or services from web endpoints.
MQTT over TCP requires what transport property?
A Unreliable datagrams
B Out-of-order frames
C Ordered byte stream
D One-way broadcast
Answer: C. Ordered byte stream. MQTT requires an ordered, lossless, bidirectional byte stream; TCP/IP is a common transport.
During Bluetooth LE advertising, how can a device communicate?
A Satellite uplink
B Connectionless advertising
C Optical signaling
D Wired serial exchange
Answer: B. Connectionless advertising. Bluetooth LE advertising supports connectionless communication and device discovery.
At the 802.15.4 layer, what does the standard specify?
A Web markup
B Application logic
C Cloud storage
D PHY and MAC
Answer: D. PHY and MAC. IEEE 802.15.4 defines physical and MAC layers for low-rate wireless personal area networks.
CoAP clients discover resources through which standard URI?
A /api/discover
B /mqtt/status
C /device/index
D /.well-known/core
Answer: D. /.well-known/core. RFC 7252 defines /.well-known/core as the well-known URI for discovering CoAP resources.