If the international flight is alternate, do passengers have to check in at the alternate destination?

In case of alternate flight, the service staff will lead the passengers to the waiting room. As long as you don't go out through the passage next to the ticket gate, you don't need to go through the security check. If the waiting time is longer (more than four hours), the airline will arrange to rest in a nearby hotel. When you return to the airport, you need to go through security check. Airlines can be required to set up a separate green security channel.