title: What is the equivalent of hd param authentication for AuthSub in OAuth2
body: <p>In AuthSub, for Google Apps hosted domains I could use the hd parameter to redirect the user to that domain, get them to login to that domain and receive the token.</p>
  
  <p>What is the equivalent functionality in OAuth2?</p>
  
  <p>I came across this URL: <a href="https://developers.google.com/drive/delegation" rel="nofollow">https://developers.google.com/drive/delegation</a></p>
  
  <p>Is this the only way? From what I understand, the service account gets direct access to all the users? The workflow would be different from what used to be for AuthSub, where the user had to login to their individual domain account? Is this understanding correct?</p>