Which protocol interacts asynchronously over UDP? Explanation: CoAP is an application layer protocol (IETF draft) for resource constrained devices. It is Asynchronous message interactions over UDP, Request/Response semantics CoAP resources are identified by Uniform Resource Identifiers.

Which protocol is used to link all the devices in the IoT *?

Due to this attribute, Bluetooth is the leading protocol used by IoT devices. It is presently used by all major operating systems such as iOS, Android, Windows Phone, Blackberry, OS X, Linux, and Windows.

What is MQTT primarily used for?

MQTT is used for data exchange between constrained devices and server applications. It keeps bandwidth requirements to an absolute minimum, handles unreliable networks, requires little implementation effort for developers, and is, therefore, ideal for machine-to-machine (M2M) communication.