After the First Referee signals to serve, a re-serve occurs in all cases except when the server:

When a re-serve is called, it typically occurs due to an error in the serving process that requires the server to have another opportunity to serve. In the case where the server swings and misses the tossed ball, it results in a re-serve, as this is considered an incomplete action. However, if the server swings, misses, and the ball inadvertently contacts their shoulder, this is classified differently. The contact with the shoulder means that the serve has been executed, albeit unsuccessfully, rather than just being a failed attempt without any contact. Thus, a re-serve is not granted in this situation since the server has technically made an attempt by engaging with the ball, regardless of the fact that it did not travel over the net.

Each of the other options presents scenarios that either do not involve an attempt to serve or involve conditions leading to no consequence for the serving attempt, thereby justifying a re-serve. For instance, allowing the tossed ball to drop or catching a bad toss indicates the server did not initiate an attempt at serving and would typically lead to a re-serve being granted.