Which of the following actions is NOT allowed during a serve?

When serving in volleyball, a player must adhere to specific rules regarding their position and actions. Stepping on or over the service line is a violation because it means the server is ascertaining the serve's legality from the wrong position. The rule dictates that the server must remain behind the service line until the ball is struck. This ensures that the serve is initiated from the designated area.

In contrast, using both hands to strike the ball is permissible, provided the release is consistent with the setup for the serve. Serving from within the court lines is also allowed, as long as the server takes a position behind the service line at the moment of the serve. Additionally, striking the ball after a toss is a legal action, as players often toss the ball for a better hit.

The emphasis on serving from the correct position without infringing on the service line is vital for maintaining the integrity of the game's official rules.