explicit timed global protocol Dns(role Client, role Server, role Other)
{
    query(Addr, Packet) connect Client to Server within [0;1] using a and resetting ();

    choice at Server {
        dummy() connect Server to Other within [0;1] using a and resetting ();
        answer(Addr, Packet) from Server to Client within [0;1] using a and resetting ();
    } or {
        query(Addr, Packet) connect Server to Other within [0;1] using a and resetting ();
        answer(Addr, Packet) from Other to Server within [0;1] using a and resetting ();
        answer(Addr, Packet) from Server to Client within [0;1] using a and resetting ();
    }
}