1.5 Prerequisites/Preconditions

When the caller doesn’t know the URL to use to communicate with the server that hosts the domain of interest, the caller performs one of the following two procedures to reach the server that can provide the information.

To reach the server by using a direct attempt:

1. Compose URLs for Autodiscover endpoints (2), where {0} is the domain of interest, in the following order:

   U1: https://autodiscover.{0}/autodiscover/autodiscover.svc

   U2: https://{0}/autodiscover/autodiscover.svc

2. Call the GetFederationInformation (section 3.1.4.2) operation at the Autodiscover endpoints (2) U1 and U2. Use the results from the first discovered URL that provides a successful response.

3. Follow HTTP 302 redirects only to HTTPS URLs.

To reach the server by using an indirect attempt:

1. Probe for an HTTP 302 redirect on a non-Secure Sockets Layer (SSL) endpoint (2).

2. Compose the URL for an Autodiscover endpoint (2), where {0} is the domain of interest:

   http://autodiscover.{0}/autodiscover/autodiscover.xml

   The response is an HTTP 302 redirect. The redirect URL in response starts with https:// and ends with /autodiscover/autodiscover.xml.

3. Parse the host element of the URL and compose the following URL, where {0} is the host element of the previous URL:

   https://{0}/autodiscover/autodiscover.svc

4. Call the GetFederationInformation operation at the Autodiscover endpoint (2).

5. Follow HTTP 302 redirects only to HTTPS URLs.