6.1.1.2.2.1.2.1.2 Connection Object

An nTDSConnection object represents a path for replication from a source DC to a destination DC. This object is a child of the nTDSDSA object of the destination DC. See section 6.2 for more information about connection objects.

Each nTDSConnection object has the following attributes:

parent: nTDSDSA object

objectClass: nTDSConnection

enabledConnection: Indicates whether the connection can be used for replication.

fromServer: A reference to the nTDSDSA object of the source DC.

schedule: Contains a SCHEDULE structure specifying the time intervals when replication can be performed between the source and the destination DCs. In case of intrasite replication (source and destination DCs are in the same site), the value of this attribute is derived from the schedule attribute on the nTDSSiteSettings object of the site where the two DCs reside. In case of intersite replication (source and destination DCs are in different sites), the value is derived from the schedule attribute on the siteLink object that links the two sites.

systemFlags: {FLAG_CONFIG_ALLOW_RENAME | FLAG_CONFIG_ALLOW_MOVE}

options: One or more bits from the following diagram. The bits are presented in big-endian byte order.


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X: Unused. Must be zero and ignored.

IG (NTDSCONN_OPT_IS_GENERATED, 0x00000001): The nTDSConnection object was generated by the KCC. See section 6.2 for more information.

TS (NTDSCONN_OPT_TWOWAY_SYNC, 0x00000002): Indicates that a replication cycle MUST be performed in the opposite direction at the end of a replication cycle that is using this connection.

OND (NTDSCONN_OPT_OVERRIDE_NOTIFY_DEFAULT, 0x00000004): Do not use defaults to determine notification.

UN (NTDSCONN_OPT_USE_NOTIFY, 0x00000008): The source DC notifies the destination DC regarding changes on the source DC.

DIC (NTDSCONN_OPT_DISABLE_INTERSITE_COMPRESSION, 0x00000010): For intersite replication, this indicates that the compression of replication data is disabled.

UOS (NTDSCONN_OPT_USER_OWNED_SCHEDULE, 0x00000020): For KCC-generated connections, indicates that the schedule attribute is owned by the user and MUST not be modified by the KCC. See section 6.2 for more information.

transportType: A reference to the interSiteTransport object for the transport used on this connection. For more information about physical transport types, see [MS-SRPL].

mS-DS-ReplicatesNCReason: For each NC that is replicated using this connection, this attribute contains an Object(DN-Binary) value, where the DN portion is the DN of the NC, and the binary value is a 32-bit–wide bit field. The binary portion contains extended information about a connection object that could be used by administrators. It consists of one or more bits from the following diagram. The bits are presented in big-endian byte order.


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X: Unused. Must be zero and ignored.

GC (NTDSCONN_KCC_GC_TOPOLOGY, 0x00000001): Not used.

R (NTDSCONN_KCC_RING_TOPOLOGY, 0x00000002): The connection object is created to form a ring topology.

MH (NTDSCONN_KCC_MINIMIZE_HOPS_TOPOLOGY, 0x00000004): The connection object is created to minimize hops between replicating nodes.

SS (NTDSCONN_KCC_STALE_SERVERS_TOPOLOGY, 0x00000008): If the KCC finds that the destination server is not responding, then it sets this bit.

OC (NTDSCONN_KCC_OSCILLATING_CONNECTION_TOPOLOGY, 0x00000010): The KCC sets this bit if deletion of the connection object was prevented.

When the KCC considers deleting a connection object, it first checks if it previously deleted connection objects with the same source DC, destination DC, and options for an implementation-specific number of times T (default value is 3) over the last implementation-specific time period t (the default is 7 days) since the server has started. If it did, it will set the NTDSCONN_KCC_OSCILLATING_CONNECTION_TOPOLOGY bit on the connection object and will not delete it. Otherwise, it will delete the connection object.

ISG (NTDSCONN_KCC_INTERSITE_GC_TOPOLOGY, 0x00000020): This connection is to enable replication of partial NC replica between DCs in different sites.

IS (NTDSCONN_KCC_INTERSITE_TOPOLOGY, 0x00000040): This connection is to enable replication of a full NC replica between DCs in different sites.

SF (NTDSCONN_KCC_SERVER_FAILOVER_TOPOLOGY, 0x00000080): This connection is a redundant connection between DCs that is used for failover when other connections between DCs are not functioning.

SIF (NTDSCONN_KCC_SITE_FAILOVER_TOPOLOGY, 0x00000100): This connection is a redundant connection between bridgehead DCs in different DCs; it is used for failover when other connections between bridgehead DCs connecting two sites are not functioning.

RS (NTDSCONN_KCC_REDUNDANT_SERVER_TOPOLOGY, 0x00000200): Redundant connection object connecting bridgeheads in different sites.

The connection object is for server-to-server replication implementation only. Peer DCs MAY assign a meaning to it, but it is not required for interoperation with Windows clients.

See section 6.2 for more information about these options.