Free Certified Wireless IoT Connectivity Professional Practice Questions

Sample Practice Questions

Try these 10 sample questions from the Certified Wireless IoT Connectivity Professional practice bank. Each includes the answer and explanation. Continue with the interactive practice above to review the full question set.

1. 1A building needs local wireless paths that can recover when an intermediate link fails. Which architectural feature of Thread addresses this requirement?

   1. A. A dedicated point-to-point link between every sensor and its controller
   2. B. A self-healing mesh that can use alternative forwarding paths
   3. C. A single-hop star that requires every sensor to reach one central radio
   4. D. A point-to-multipoint layout with fixed paths through one central node

   Answer: B

   Explanation: The Thread primer lists "Reliability — Self-healing mesh networking, with no single point of failure". Alternative mesh paths address recovery from a failed intermediate link; the other layouts describe fixed direct or central paths.

   Reference: Thread Primer: What is Thread? — What is Thread? — primary features, Reliability

2. 2How does the wavelength of a radio signal change when its carrier frequency increases while propagation speed remains constant?

   1. A. It increases in direct proportion to frequency
   2. B. It remains constant because propagation speed is unchanged
   3. C. It decreases in inverse proportion to frequency
   4. D. It increases in proportion to the square of frequency

   Answer: C

   Explanation: TI defines "λ: Wavelength; where λ = c / f". At fixed c, increasing f decreases wavelength inversely. The other choices confuse propagation speed with wavelength or reverse the relationship.

   Reference: Achieving Optimum Radio Range — Section 2.4 Friis-Equation, page 4, variable definitions

3. 3For the IEEE 802.15.4-2006 2.4 GHz PHY, what is the spacing between adjacent channel centers numbered 11 through 26?

   1. A. 1 MHz
   2. B. 2 MHz
   3. C. 5 MHz
   4. D. 10 MHz

   Answer: C

   Explanation: TI states, "They are numbered 11 through 26 and are 5 MHz apart." These are the standard channel centers, distinct from the CC2520's finer frequency-programming resolution.

   Reference: CC2520 Datasheet: 2.4 GHz IEEE 802.15.4/Zigbee RF Transceiver — Section 16 Frequency and Channel Programming, page 62

4. 4In an IEEE 802.15.4 data frame, which MAC header indication asks the recipient to send an acknowledgment?

   1. A. The destination addressing mode
   2. B. The frame-pending indication
   3. C. The acknowledgment-request bit
   4. D. The source PAN identifier

   Answer: C

   Explanation: TI's acknowledgment conditions include "The acknowledgment request bit must be set in the RX frame". The FCF contains this request. Frame pending reports pending traffic, while addresses identify the participants rather than request an ACK.

   Reference: CC2520 Datasheet: 2.4 GHz IEEE 802.15.4/Zigbee RF Transceiver — Page 81 — Acknowledgement Transmission — Automatic Control

5. 5Which role forms a centralized Zigbee network and subsequently participates as a router?

   1. A. A sleepy end device
   2. B. A cluster client
   3. C. A minimal end device
   4. D. The Zigbee coordinator

   Answer: D

   Explanation: Silicon Labs states, "A Zigbee coordinator (ZC) is responsible for forming a centralized network." It adds, "After forming the network, the coordinator acts as a router." End-device classifications and application cluster roles do not provide this network-formation function.

   Reference: UG103.2: Zigbee Fundamentals — Section 3.1 Coordinator, page 6

6. 6An IoT design selects AES-256. What is the AES data-block size, as distinct from its key length?

   1. A. 128 bits
   2. B. 192 bits
   3. C. 256 bits
   4. D. 512 bits

   Answer: A

   Explanation: FIPS 197 states, "Each of them transforms data in blocks of 128 bits, and the numerical suffx indicates the bit length of the associated cryptographic keys." AES-256 uses a 256-bit key but retains the 128-bit AES block size. The other values confuse block length with key or digest lengths.

   Reference: FIPS 197: Advanced Encryption Standard (AES) — Abstract, page ii

7. 7During an IoT range test, an engineer must locate intermittent RF activity by frequency across the operating band and nearby channels, including nondecodable signals. Which measurement setup is appropriate?

   1. A. A packet decoder retaining only valid frames on the operating channel
   2. B. A spectrum analyzer using max hold across the relevant frequency span
   3. C. A broadband RF power meter integrating energy across its entire passband
   4. D. A spectrum analyzer in zero span at only the nominal carrier frequency

   Answer: B

   Explanation: TI recommends "using a spectrum analyzer (max hold) to look for RF sources prior to performing the test." A frequency sweep with max hold retains intermittent activity across the surveyed span. Valid-frame capture can miss nondecodable interference, integrated power does not locate it by frequency, and a single zero-span frequency does not survey nearby channels.

   Reference: Achieving Optimum Radio Range — Section 2.5.2 Immunity to Unwanted RF Signals, page 7

8. 8Which description matches the LoRaWAN architecture used to carry measurements from end devices to a central network server?

   1. A. End devices form a peer mesh and forward one another's measurements
   2. B. End devices connect in a ring and pass measurements through adjacent devices
   3. C. End devices use a chain of end-device relays before reaching the server
   4. D. End devices use single-hop radio links to gateways in a star-of-stars topology

   Answer: D

   Explanation: The Alliance states, "The LoRaWAN® network architecture uses a star-of-stars topology, where gateways relay messages between end-devices and a central network server." It also states, "The LoRa® physical layer’s long-range capability allows single-hop links between end-devices and gateways." The alternatives mistakenly make end devices transit relays.

   Reference: LoRa Alliance: What is LoRaWAN? — Getting Started with LoRaWAN — LoRaWAN Architecture

9. 9Which group consists entirely of sub-1 GHz ISM frequencies listed in TI's low-power radio propagation discussion?

   1. A. 433 MHz, 868 MHz, and 915 MHz
   2. B. 433 MHz, 915 MHz, and 2.4 GHz
   3. C. 868 MHz, 2.4 GHz, and 5.8 GHz
   4. D. 915 MHz, 2.4 GHz, and 5 GHz

   Answer: A

   Explanation: TI lists common ISM bands at "169 MHz, 315 MHz, 433 MHz, 490 MHz, 780 MHz, 868 MHz, 915 MHz and 2.4 GHz". The first group contains only listed frequencies below 1 GHz. Each other group includes at least one GHz-band frequency above that boundary; this classification does not grant regulatory permission to operate.

   Reference: Achieving Optimum Radio Range — Section 2.1 Propagation, page 2

10. 10How is each 4-bit data symbol spread in the IEEE 802.15.4-2006 2.4 GHz DSSS modulation described by TI?

    1. A. It selects one of 16 sequences containing 32 chips each
    2. B. It selects one of 32 sequences containing 16 chips each
    3. C. It selects one of 4 sequences containing 8 chips each
    4. D. It selects one of 8 sequences containing 4 chips each

    Answer: A

    Explanation: TI states, "Each symbol is mapped to one out of 16 pseudo-random sequences, 32 chips each." The alternatives interchange the number of available symbols, chips per sequence, and bits per symbol.

    Reference: CC2520 Datasheet: 2.4 GHz IEEE 802.15.4/Zigbee RF Transceiver — Section 17 IEEE 802.15.4-2006 Modulation Format, page 63