Owners of AirBnB properties or similar room rental services are required to operate a register of guests (Gästeverzeichnis) for guests staying short-term. Only in the case of guests staying for more than two months are they required to do their own MeldebestätigungMeldezettel Austria requires everyone living in Austria (both Austrians and foreigners) to register their place(s) of residence with the local authorities. The confirmation of this registration is called a Meldebestätigung (EN: confirmation of registration), although it is still affectionately known to many by its former name (the Meldezettel). This is done at your Meldeamt in the Gemeinde or Bezirk you live in. You are required to do your registration within three days of arrival. It is important to do this also because your qualification for permanent residence starts to run from the point of your registration. (confirmation of registration).
Stadt Wien information in German about the Gästeverzeichnis.