Which protocol is used for communication between the instance and MID?

The correct choice is SOAP over HTTPS because this protocol is specifically designed for communication between the ServiceNow instance and the Management Instance (MID) server. SOAP (Simple Object Access Protocol) operates over HTTP, and when combined with HTTPS (HTTP Secure), it ensures that the data exchanged is encrypted during transmission. This is crucial for maintaining the security and confidentiality of sensitive information that might be sent between the two entities.

SOAP is widely used in enterprise environments because it provides standards for messaging, allowing for communication between different applications that might be running on various platforms. It also supports advanced features such as transaction management, which is important in complex integrations. Given these characteristics, SOAP over HTTPS is well-suited for the secure and reliable data exchange required between the MID and an instance.