For a time-critical motor response, where should the control loop run?
A Public web page
B Email server
C Local edge controller
D Distant cloud region
Answer: C. Local edge controller. Running the control loop locally reduces dependence on a remote connection and can lower response delay.
During an uplink outage, what can preserve readings for later delivery?
A Cloud-only queue
B Local buffer
C Discarding data
D Immediate retransmission
Answer: B. Local buffer. A local buffer stores readings temporarily so they can be forwarded when connectivity returns.
Battery sensors report periodically. Which method limits radio-on time?
A Continuous scanning
B Full-time polling
C Maximum retransmission
D Duty cycling
Answer: D. Duty cycling. Duty cycling schedules active and sleep periods to reduce energy use.
Publishers need not know each MQTT receiver. What decouples them?
A IP address
B Sensor actuator
C Power supply
D Message broker
Answer: D. Message broker. The broker accepts publications and routes them to matching subscribers, decoupling senders from receivers.
Slowly drifting sensor values call for which maintenance action?
A Recalibration
B Route discovery
C Key rotation
D Packet framing
Answer: A. Recalibration. Recalibration compares measurements with a known reference and corrects drift.
If an edge filter drops irrelevant samples, what can it reduce?
A Network traffic
B Clock accuracy
C Device identity
D Sensor range
Answer: A. Network traffic. Sending fewer relevant summaries reduces network traffic and often storage needs.
Multiple factories need long-term cross-site analysis. Where does it fit?
A Local controller
B Single gateway
C Cloud platform
D Sensor firmware
Answer: C. Cloud platform. A cloud platform can combine and analyze data from many sites over time.
Connecting BLE sensors to IP, what role does the hub perform?
A Temperature sensor
B RFID tag
C Firmware compiler
D Protocol gateway
Answer: D. Protocol gateway. The hub bridges different network technologies and may translate their protocols.
In a W3C Thing Description, what affordance represents readable state?
A Property
B Action
C Protocol
D Event
Answer: A. Property. A Property describes a Thing’s state and may be readable or writable through an interaction.
Invoking a Thing operation is represented by which W3C affordance?
A Property
B Action
C Topic
D Event
Answer: B. Action. An Action affordance represents a function that a consumer can invoke on a Thing.
Asynchronous notifications use which WoT affordance?
A Event
B Action
C Binding
D Property
Answer: A. Event. An Event affordance describes an event source that can push data asynchronously.
After one mesh link fails, what can keep traffic moving?
A Central broker
B Single uplink
C Static lease
D Alternate route
Answer: D. Alternate route. A mesh may provide alternate paths through other nodes when a link becomes unavailable.
Failure of what star component may isolate many endpoints?
A Single leaf route
B Central hub failure
C Cloud backup
D One sensor battery
Answer: B. Central hub failure. A star’s endpoints depend on the central hub for communication with one another or the uplink.
To order readings from several nodes, what should clocks share?
A Synchronized time
B Common battery
C Same radio
D Matching firmware
Answer: A. Synchronized time. Synchronized timestamps help correlate and order events from separate devices.
Higher sampling frequency usually increases what first?
A Sensor accuracy
B Radio range
C Device identity
D Data volume
Answer: D. Data volume. More samples per unit time create more readings to transmit or store.
What helps track enrolled devices across a large fleet?
A Message payload
B Sensor lens
C PWM output
D Device registry
Answer: D. Device registry. A device registry records identities and metadata for managed fleet members.
With a doubled sampling rate, how many readings arrive per hour?
A Half as many
B Twice as many
C Four times as many
D No readings
Answer: B. Twice as many. At the same interval and uptime, doubling the rate doubles the number of readings.
New MQTT subscribers can receive the latest known state through which feature?
A Clean session
B Retained message
C Will delay
D QoS header
Answer: B. Retained message. The broker sends the retained message to a new subscriber whose subscription matches that topic.
When data is sent only after a threshold changes, which style fits?
A Round-robin
B Batch-only
C Event-driven
D Time-division
Answer: C. Event-driven. Event-driven reporting sends messages in response to defined changes or conditions.
Cloud loss must not stop safe local operation. What should a controller use?
A Remote-only command
B Longer dashboard
C Open network port
D Local fallback rule
Answer: D. Local fallback rule. A local fallback rule lets a control system respond safely when remote connectivity is unavailable.
Cross-vendor applications need a common device interaction model. What can help?
A DHCP lease
B WoT Thing Description
C I2C address
D JPEG metadata
Answer: B. WoT Thing Description. A W3C Thing Description models Properties, Actions, and Events using a machine-readable description.
Small radio frames favor what application payload design?
A Verbose logs
B Full database dumps
C Compact payloads
D Large images
Answer: C. Compact payloads. Compact payloads fit constrained links more efficiently and reduce airtime.
Rather than forwarding every raw sample, what can a gateway send?
A Local aggregate
B Full packet capture
C Device password
D Bootloader image
Answer: A. Local aggregate. Local aggregation summarizes multiple readings before transmission, reducing traffic.
For diagnosing intermittent sensor faults, which record helps most?
A Cached passwords
B Random topics
C Timestamped logs
D Unlabeled values
Answer: C. Timestamped logs. Timestamped logs show when faults and readings occurred, helping correlate intermittent problems.
Battery life is limited. Which change most directly cuts radio energy?
A Increase sampling
B Keep radio awake
C Reduce transmissions
D Scan continuously
Answer: C. Reduce transmissions. Fewer radio transmissions generally reduce the energy spent transmitting and waking the radio.