IoT Standards and Protocols

Correct Answer: MQTT broker with authentication

To limit access to the MQTT data to only registered devices, the smart home system should implement an MQTT broker with authentication. Authentication ensures that only authorized devices can connect to the broker and access the data. Using an MQTT broker that lacks authentication would allow any device to connect and access the data, compromising security. While an HTTP server with authentication could provide access control, it is not the appropriate protocol for device communication in this context, as MQTT is specifically designed for lightweight messaging in IoT environments. CoRE (Constrained RESTful Environments) is a protocol for resource-constrained devices, but it does not directly address the authentication requirement for limiting access to registered devices.

Correct Answer: Zigbee

Zigbee is the best choice for a wireless IoT network when power efficiency and simplicity are the main priorities. Zigbee is designed for low-power, low-data rate applications, making it ideal for battery-powered IoT devices. It operates on the 2.4 GHz, 915 MHz, and 868 MHz frequency bands, avoiding interference with Wi-Fi networks. Zigbee also has a simple protocol stack and supports mesh networking, allowing devices to relay messages and extend network coverage. In contrast, Wi-Fi consumes more power and is more complex, making it less suitable for simple IoT devices. BLE (Bluetooth Low Energy) is designed for short-range, low-power communication but lacks the mesh networking capabilities of Zigbee. LoRaWAN is designed for long-range, low-power communication but has a more complex protocol stack and is better suited for outdoor, wide-area IoT applications rather than indoor, local networks.

Correct Answer: TLS

TLS (Transport Layer Security) is the best protocol for ensuring data security and encryption for data transmission in IoT devices. TLS provides end-to-end encryption, authentication, and integrity protection, making it suitable for secure communication between IoT devices and servers. FTP (File Transfer Protocol) and HTTP (Hypertext Transfer Protocol) do not provide built-in encryption and are not secure for transmitting sensitive data. SMTP (Simple Mail Transfer Protocol) is used for email communication and is not the appropriate choice for IoT device data transmission. Therefore, TLS is the most secure and suitable option among the given choices.