Exchange 2007 Autodiscover Service

Introduction;

Microsoft Exchange Server 2007 includes a new Microsoft Exchange service named the Autodiscover
service. The Autodiscover service configures and maintains server settings for client computers that are
running Microsoft Office Outlook 2007. The Autodiscover service can also configure supported mobile
devices. An important function of the Autodiscover service is to provide access to Microsoft Exchange
features for Outlook 2007 clients that are connected to your Microsoft Exchange messaging environment.
These features include the Web-based offline address book (OAB), the Availability service, and Unified
Messaging (UM). The Autodiscover service must be deployed and configured correctly for Outlook 2007
clients to automatically connect to Microsoft Exchange features. For more information about how to
configure Exchange features, see How to Configure Exchange Services for the Autodiscover Service later
in this white paper.

How the Autodiscover Service Works with Clients ?

     When you install the Client Access server role on a computer that is running Exchange 2007, a new virtual
directory named Autodiscover is created under the Default Web Site in Internet Information Services
(IIS). This virtual directory handles Autodiscover service requests from Outlook 2007 clients in the
following circumstances:
When a new Outlook profile is configured or updated
When a client periodically checks for changes to the Exchange Web Services URLs
When underlying network connection changes occur in your Exchange messaging
environment
Additionally, a new service connection point (SCP) Active Directory object is created for each server
where the Client Access server role is installed. The SCP object is used by domain-connected clients to
locate the Autodiscover service. The SCP object contains two pieces of information, the
serviceBindingInformation attribute and the keywords attribute. The serviceBindingInformation
attribute has the Fully Qualified Domain Name (FQDN) of the Client Access server in the form of
https://cas01.contoso.com/autodiscover/autodiscover.xml, where cas01.contoso.com is the fully qualified
domain name (FQDN) for the Client Access server. The keywords attribute specifies the Active Directory
sites to which this SCP record is associated. By default, this attribute specifies the Active Directory site to
which the Client Access server belongs.
When a domain-connected client connects to the Active Directory directory service, the Exchange 2007
client authenticates to Active Directory and tries to locate the Autodiscover SCP objects that were created
during Setup by using the user's credentials. In deployments that include multiple Client Access servers,
an Autodiscover SCP record is created for each Client Access server. By using the user credentials, the
Outlook 2007 client authenticates to Active Directory and searches for the Autodiscover SCP objects. After
the client obtains and enumerates the instances of the Autodiscover service, the client connects to the
first Client Access server in the enumerated and sorted list and obtains the profile information in the form
of XML data that is needed to connect to the user's mailbox and available Microsoft Exchange features.
An Outlook 2007 client connects to the Autodiscover service as follows:
Outlook 2007 sends a Lightweight Directory Access Protocol (LDAP) query to Active Directory
looking for all available SCP objects. Specifically, Outlook initializes the LDAP connection using the
ldap_init() function and passes a NULL value for the hostname. When a particular global catalog
server name (or domain name) is not specified, the operation searches for a global catalog server
in the domain, based on the membership of the computer that is initializing the operation.

1.Outlook 2007 sorts and enumerates the returned results based on the client's Active Directory site
by using the keyword attribute of the SCP record. One of two lists is created, an in-site list or an
out-of-site list. The in-site list provides the SCP records that have AutodiscoverSiteScope
information. AutodiscoverSiteScope is a parameter that is set on the Client Access server by using
the Set-ClientAccessServer cmdlet. The parameter specifies the site for which the Autodiscover

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http://technet.microsoft.com/en-us/library/bb332063(EXCHG.80,printer).aspx 3/2/2010
service is authoritative. The AutodiscoverSiteScope information contained in the SCP records for
the in-site list matches the Active Directory site for the Outlook client. If there are no in-site
records, an out-of-site SCP record list will be generated. The list is not sorted in any particular
order. Therefore, the list is approximately in the order of oldest SCP records (based on creation
date) first.
Note:
In environments where Outlook 2007 is deployed in remote sites that do not have
Exchange 2007 Mailbox and Client Access servers, you can use site affinity to configure the
SCP objects for Outlook 2007 clients to use SCP objects that are physically closer. For more
information, see How to Configure the Autodiscover Service to Use Site Affinity later in this
white paper.
Outlook first tries to connect to each Autodiscover URL that it had previously generated from either
an in-site list or an out-of-site list. If that doesn't work, Outlook will try to connect to the
predefined URLs (for example, https://autodiscover.contoso.com/autodiscover/autodiscover.xml)
by using DNS. If that fails also, Outlook will try the HTTP redirect method and, failing that, Outlook
will try to use the SRV record lookup method. If all lookup methods fail, Outlook will be unable to
obtain Outlook Anywhere configuration and URL settings.
3. The Autodiscover service queries Active Directory to obtain the connection settings and URLs for
the Exchange services that have been configured.
4. The Autodiscover service returns an HTTPS response with an XML file that includes the connection
settings and URLs for the available Exchange services.
5. Outlook uses the appropriate configuration information and connection settings to connect to your
Exchange messaging environment.