How to use the new DNS SRV lookup method to locate the Exchange 2007 Autodiscover service

Note: the feature only works with Outlook 2007 /w SP1

To use the new DNS SRV lookup method in order to locate the Exchange 2007 Autodiscover service, follow these steps.

Note You must create the Autodiscover SRV record in the external DNS zone that matches the right side of your user's SMTP addresses. For example, if a user's primary SMTP address is user@contoso.com, the record must be created in the contoso.com external DNS zone. If you have multiple primary SMTP address domains in your organization, you must create an Autodiscover SRV record in each zone.

1. In your external DNS zone, remove any HOST (A) or CNAME records for the Autodiscover service.
2. Use the following parameters to create a new SRV record:

   Service: _autodiscover Protocol: _tcp Port Number: 443 Host: mail.contoso.com 

   Note For more information about how to create this record, see the "About SRV records" section.
3. to verify the DNS Srv record:

              nslookup -q=srv _autodiscover._tcp.contoso.com and make it returns right host name, IP address and port 443.

 

Note In this example, mail.contoso.com is a name for which your certificate is valid. Usually, this is the same DNS name that you use for Outlook Anywhere and for Outlook Web Access.

In this example, the Autodiscover service does the following when the client tries to contact the Autodiscover service:

1. Autodiscover posts to https://contoso.com/Autodiscover/Autodiscover.xml. This fails.
2. Autodiscover posts to https://autodiscover.contoso.com/Autodiscover/Autodiscover.xml. This fails.
3. Autodiscover performs the following redirect check:
   GET http://autodiscover.contoso.com/Autodiscover/Autodiscover.xml
   This fails.
4. Autodiscover uses DNS SRV lookup for _autodiscover._tcp.contoso.com, and then "mail.contoso.com" is returned.
5. Outlook asks permission from the user to continue with Autodiscover to post to https://mail.contoso.com/autodiscover/autodiscover.xml.
6. Autodiscover's POST request is successfully posted to https://mail.contoso.com/autodiscover/autodiscover.xml