Which wireless topology allows every node in an IoT sensor network to communicate with adjacent nodes, forming self-healing redundant paths?
Mesh networks (e.g., Zigbee Mesh, Thread, Wi-Fi Mesh) provide self-configuring and self-healing redundant data paths across nodes.
What is 'Last Will and Testament' (LWT) feature in MQTT protocol?
LWT enables brokers to notify other clients automatically when an IoT device unexpectedly loses power or connection.
Which protocol feature enables a CoAP client to receive automatic resource state updates from a server without continuously polling?
The CoAP Observe extension allows a client to register interest in a resource; the server then pushes state changes to the client.
Which layer of the OSI model does the MQTT protocol operate at?
MQTT is an Application layer messaging protocol that runs on top of TCP/IP.
What is the maximum payload size typically recommended for a single CoAP packet over UDP to avoid IP fragmentation?
CoAP messages are kept small (typically <1024 bytes) to fit within a single IEEE 802.15.4 frame or UDP packet without fragmentation.