Creating an Application Directory Partition

An application directory partition is represented by a domainDNS object with an instanceType attribute value of DS_INSTANCETYPE_IS_NC_HEAD combined with DS_INSTANCETYPE_NC_IS_WRITEABLE. This domainDNS object represents the application directory partition root (NC head), and is named similar to a regular domain partition, for example, DC=dynamicdata,DC=fabrikam,DC=com, which corresponds to a DNS name of dynamicdata.fabrikam.com. An application directory partition can, therefore, be instantiated anywhere a domain partition can be instantiated. There is no NetBIOS name associated with an application directory partition.

It is possible to nest application directory partitions, that is, an application directory partition can have child application directory partitions. Searches with subtree scope rooted at an application directory partition head will generate continuation references to the child application directory partitions.

An application directory partition replica can only be created on a domain controller that is running on Windows Server 2003 or later and only while the Domain-Naming FSMO role is held by a Windows Server 2003 or later domain controller. In a mixed forest that has both Windows Server 2003 domain controllers and down-level domain controllers (Windows 2000 domain controllers or Windows NT 4.0 primary domain controllers), an attempt to create an application directory partition replica on a down-level domain controller will fail.

An application directory partition also has a corresponding crossRef object in the Partitions container of the configuration partition. The crossRef can be pre-created manually before creating the domainDNS object. The pre-created crossRef object must have the attribute values shown in the following table or the partition creation will fail. If the crossRef object does not exist, Active Directory will create one when the application directory partition is created.

To create a new application directory partition with its first replica, perform the following steps

1. Bind to the namespace for the new partition, specifying the domain controller that will host the application directory partition in the ADsPath. For example, to create a partition with an ADsPath of DC=dynamicdata,DC=mydomain,DC=com, the binding ADsPath would be LDAP://<domain controller>/DC=mydomain,DC=com, where <domain controller> is the DNS name of the domain controller that will host the partition.

   The bind operation must specify the fast and delegation options. The fast option allows the bind to succeed even if the namespace does not exist. The delegation option is required to allow the domain controller to contact the Domain-Naming FSMO role holder using the same credentials.

   The system version of the domain controller must be Windows Server 2003 operating system or later.

2. Create a domainDNS object with an appropriate name for the partition, for example, DC=dynamicdata, to represent the naming context head for the new partition. The domainDNS object must have an instanceType attribute with a value of 5 (DS_INSTANCETYPE_IS_NC_HEAD | DS_INSTANCETYPE_NC_IS_WRITEABLE). The instanceType attribute can only be set at creation time because it is a system-only attribute.

When the domainDNS object is created, Active Directory will perform the following steps:

1. Searches for a crossRef object in the Partitions container that has an nCName attribute value that matches the distinguished name of the partition and, if a match is found, modifies the crossRef object to represent the application directory partition. If a matching crossRef object is not found, Active Directory creates a new crossRef object to represent the application directory partition.

   The following table lists important attributes of the crossRef object.

   Attribute	Description
   nCName	Contains the distinguished name of the partition.
   dnsRoot	Contains the DNS name of the partition.
   msDS-NC-Replica-Locations	The distinguished name of the nTDSDSA object of the domain controller for the first replica is added to this attribute.

2. Initiate a synchronization of the configuration partition and wait for completion. This enables the client application to modify configuration parameters for the newly created application directory partition while bound to the same domain controller used for creating the application directory partition.
3. Create the domainDNS object with the DS_INSTANCETYPE_IS_NC_HEAD and DS_INSTANCETYPE_NC_IS_WRITEABLE flags set on the instanceType property. The instanceType property may contain other, private flags as well.
4. Populate the ms-DS-Has-Master-NCs attribute of the nTDSDSA object for the target domain controller with the distinguished name of the newly created application directory partition.

When the application directory partition is created, or when a new replica of the application directory partition is added and fully synchronized, Active Directory correctly registers the replica with NetLogon and DNS. For more information, and a list of the registered SRV records, see Locating an Application Directory Partition Host Server.

For more information about creating an application directory partition, see Example Code for Creating an Application Directory Partition.

Locating the Partitions Container

The distinguished name of the Partitions container can be found in one of two ways. The first is more complicated to perform, but will always provide an accurate result:

1. Bind to RootDSE and obtain the configurationNamingContext attribute.
2. Use the configurationNamingContext attribute to bind to the configuration container.
3. Search in the configuration container for an object that is of the crossRefContainer type.
4. Obtain the distinguishedName attribute value of the crossRefContainer object. This will be the distinguished name of the Partitions container.

The second method is easier to implement, but relies on the Partitions container having a particular relative distinguished name. It is not currently possible to change the name of the Partitions container, but if this capability is added in the future, the procedure below will not work correctly if the Partitions container has been renamed.

1. Bind to RootDSE and obtain the configurationNamingContext attribute.
2. Combine the string CN=Partitions, followed by the configurationNamingContext attribute to form the distinguished name of the Partitions container. The distinguished name will be in the form CN=Partitions,<configuration DN>.