RFC977 3.11.1.  QUIT

   QUIT

   The server process acknowledges the QUIT command and then closes the
   connection to the client.  This is the preferred method for a client
   to indicate that it has finished all its transactions with the NNTP
   server.

   If a client simply disconnects (or the connection times out, or some
   other fault occurs), the server should gracefully cease its attempts
   to service the client.

RFC977 3.11.2.  Responses

   205 closing connection - goodbye!