This document uses the following terms:
8.3 name: A file name string restricted in length to 12 characters that includes a base name of up to eight characters, one character for a period, and up to three characters for a file name extension. For more information on 8.3 file names, see [MS-CIFS] section 188.8.131.52.1.
Access Based Directory Enumeration (ABDE) mode: A mode where the server filters directory entries according to the access permissions of the client. In a DFS scenario, ABDE is enabled on the DFS root target share to prevent a user from seeing another user's home directory. The DFS namespace administrator can create a DFS link for a user (or user group), and a user is granted appropriate rights to the DFS link.
access control list (ACL): A list of access control entries (ACEs) that collectively describe the security rules for authorizing access to some resource; for example, an object or set of objects.
Active Directory: The Windows implementation of a general-purpose directory service, which uses LDAP as its primary access protocol. Active Directory stores information about a variety of objects in the network such as user accounts, computer accounts, groups, and all related credential information used by Kerberos [MS-KILE]. Active Directory is either deployed as Active Directory Domain Services (AD DS) or Active Directory Lightweight Directory Services (AD LDS), which are both described in [MS-ADOD]: Active Directory Protocols Overview.
Active Directory Domain Services (AD DS): A directory service (DS) implemented by a domain controller (DC). The DS provides a data store for objects that is distributed across multiple DCs. The DCs interoperate as peers to ensure that a local change to an object replicates correctly across DCs. AD DS is a deployment of Active Directory [MS-ADTS].
authentication level: A numeric value indicating the level of authentication or message protection that remote procedure call (RPC) will apply to a specific message exchange. For more information, see [C706] section 184.108.40.206 and [MS-RPCE].
binary large object (BLOB): A discrete packet of data that is stored in a database and is treated as a sequence of uninterpreted bytes.
clustered DFS namespace: A stand-alone DFS namespace that is hosted on a file server cluster.
Coordinated Universal Time (UTC): A high-precision atomic time standard that approximately tracks Universal Time (UT). It is the basis for legal, civil time all over the Earth. Time zones around the world are expressed as positive and negative offsets from UTC. In this role, it is also referred to as Zulu time (Z) and Greenwich Mean Time (GMT). In these specifications, all references to UTC refer to the time at UTC-0 (or GMT).
DFS namespace name: The second path component of a DFS path. In the DFS path \\MyDomain\MyDfs\MyDir, the DFS namespace name is MyDfs.
DFS server: A server computer that runs the DFS service required to respond to DFS referral requests. Also interchangeably used to refer to the DFS service itself.
DFS target: Either a DFS root target server or a DFS link target server.
directory service (DS): A service that stores and organizes information about a computer network's users and network shares, and that allows network administrators to manage users' access to the shares. See also Active Directory.
distinguished name (DN): A name that uniquely identifies an object by using the relative distinguished name (RDN) for the object, and the names of container objects and domains that contain the object. The distinguished name (DN) identifies the object and its location in a tree.
Distributed File System (DFS): A file system that logically groups physical shared folders located on different servers by transparently connecting them to one or more hierarchical namespaces. DFS also provides fault-tolerance and load-sharing capabilities.
Distributed File System (DFS) client: A computer that is used to access a DFS namespace. It also can refer to the DFS software on a client that accesses the DFS namespace.
Distributed File System (DFS) client target failback: An optional feature that, when enabled, permits a DFS client to revert to a more optimal DFS target at an appropriate time after a DFS client target failover. The term "failback" refers to DFS client target failback. The DFS Referral Protocol, as specified in [MS-DFSC], describes the mechanisms by which a DFS server provides a list of DFS targets in decreasing order of optimality to the client.
Distributed File System (DFS) in-site referral mode: A mode in which DFS root or DFS link referral requests to a DFS server result in DFS referral responses with only those DFS targets in the same Active Directory Domain Services (AD DS) site as the DFS client requesting the DFS referral. When this mode is disabled, there is no restriction on the AD DS site of the targets returned in the referral response. This can be enabled per DFS namespace. If there are no DFS targets in the same AD DS site as the client, the DFS referral response may be empty.
Distributed File System (DFS) interlink: A special form of DFS link whose link target is a DFS domain-based namespace.
Distributed File System (DFS) link: A component in a DFS path that lies below the DFS root and maps to one or more DFS link targets. Also interchangeably used to refer to a DFS path that contains the DFS link.
Distributed File System (DFS) link target: The mapping destination of a link. A link target can be any Universal Naming Convention (UNC) path. For example, a link target could be a share or another Distributed File System (DFS) path.
Distributed File System (DFS) metadata: Information about a Distributed File System (DFS) namespace such as namespace name, DFS links, DFS link targets, and so on, that is maintained by a DFS server. For domain-based DFS, the metadata is stored in an Active Directory Domain Services (AD DS) object corresponding to the DFS namespace. For a stand-alone DFS namespace, the DFS root target stores the DFS metadata in an implementation-defined manner; for example, in the registry.
Distributed File System (DFS) namespace: A virtual view of shares on different servers as provided by DFS. Each file in the namespace has a logical name and a corresponding address (path). A DFS namespace consists of a root and many links and targets. The namespace starts with a root that maps to one or more root targets. Below the root are links that map to their own targets.
Distributed File System (DFS) namespace, domain-based: A DFS namespace that has configuration information stored in the Active Directory directory service. The DFS namespace may span over a distributed system that is organized hierarchically into logical domains, each with a domain controller (DC). The path to access the root or a link starts with the host domain name. A domain-based DFS root can have multiple root targets, which offers fault tolerance and load sharing at the root level.
Distributed File System (DFS) namespace, standalone: A DFS namespace that has metadata stored locally on the host server. The path to access the root or a link starts with the host server name. A stand-alone DFS root has only one root target. Stand-alone roots are not fault-tolerant; when the root target is unavailable, the entire DFS namespace is inaccessible. Stand-alone DFS roots can be made fault tolerant by creating them on clustered file servers.
Distributed File System (DFS) path: Any Universal Naming Convention (UNC) path that starts with a DFS root and is used for accessing a file or directory in a DFS namespace.
Distributed File System (DFS) referral: A DFS client issues a DFS referral request to a DFS root target or a DC, depending on the DFS path accessed, to resolve a DFS root to a set of DFS root targets, or a DFS link to a set of DFS link targets. The DFS client uses the referral request process as needed to finally identify the actual share on a server that has accessed the leaf component of the DFS path. The request for a DFS referral is referred to as DFS referral request, and the response for such a request is referred to as DFS referral response.
Distributed File System (DFS) referral site costing: When appropriately enabled for a DFS namespace, an optional feature that results in a DFS referral response. In the referral response, targets are grouped into sets based on increasing Active Directory Domain Services (AD DS) site cost from the DFS client that is requesting the referral to the DFS target server. When this feature is disabled, the referral response consists of at most two target sets: one set consisting of all DFS targets in the same AD DS site as the DFS client, and the other set consisting of DFS targets that are not in the same AD DS site as the DFS client.
Distributed File System (DFS) root: The starting point of the DFS namespace. The root is often used to refer to the namespace as a whole. A DFS root maps to one or more root targets, each of which corresponds to a share on a separate server. A DFS root has one of the following formats "\\<ServerName>\<RootName>" or "\\<DomainName>\<RootName>". Where <ServerName> is the name of the root target server hosting the DFS namespace; <DomainName> is the name of the domain that hosts the DFS root; and <RootName> is the name of the root of a domain-based DFS. The DFS root must reside on an NTFS volume.
Distributed File System (DFS) root scalability mode: Domain-based DFS root targets normally poll the primary domain controller (PDC) to check for any change in the DFS metadata of a DFS namespace. When the DFS server on a DFS root target supports this mode, and it is enabled for a DFS namespace, the DFS server instead polls a domain controller (DC) closer to it in terms of Active Directory Domain Services (AD DS) site cost.
Distributed File System (DFS) root target: A server that hosts a DFS root of a DFS namespace. A domain-based DFS namespace can have multiple DFS root targets; a standalone DFS namespace can have only one DFS root target.
Distributed File System (DFS) server: A server computer running the DFS service that responds to DFS referral requests, as specified in [MS-DFSC], as well as to the DFS: Namespace Management Protocol. Also used interchangeably to refer to the DFS service itself.
domain: A set of users and computers sharing a common namespace and management infrastructure. At least one computer member of the set must act as a domain controller (DC) and host a member list that identifies all members of the domain, as well as optionally hosting the Active Directory service. The domain controller provides authentication of members, creating a unit of trust for its members. Each domain has an identifier that is shared among its members. For more information, see [MS-AUTHSOD] section 220.127.116.11 and [MS-ADTS].
domain controller (DC): The service, running on a server, that implements Active Directory, or the server hosting this service. The service hosts the data store for objects and interoperates with other DCs to ensure that a local change to an object replicates correctly across all DCs. When Active Directory is operating as Active Directory Domain Services (AD DS), the DC contains full NC replicas of the configuration naming context (config NC), schema naming context (schema NC), and one of the domain NCs in its forest. If the AD DS DC is a global catalog server (GC server), it contains partial NC replicas of the remaining domain NCs in its forest. For more information, see [MS-AUTHSOD] section 18.104.22.168.2 and [MS-ADTS]. When Active Directory is operating as Active Directory Lightweight Directory Services (AD LDS), several AD LDS DCs can run on one server. When Active Directory is operating as AD DS, only one AD DS DC can run on one server. However, several AD LDS DCs can coexist with one AD DS DC on one server. The AD LDS DC contains full NC replicas of the config NC and the schema NC in its forest. The domain controller is the server side of Authentication Protocol Domain Support [MS-APDS].
domain-based DFS namespace: A DFS namespace that has configuration information stored in domain services. The DFS namespace can span a distributed system that is organized hierarchically into logical domains. The path to access a domain-based DFS namespace starts with the host domain name. A domain-based DFS namespace can have multiple DFS root targets, which offers high availability and load sharing at the DFS root level.
domainv1-based DFS namespace: A type of domain-based DFS namespace that has its DFS metadata stored in directory services as an ftDfs type object.
domainv2-based DFS namespace: A type of domain-based DFS namespace that has its DFS metadata stored in the form of individual LDAP entries, with one LDAP entry per DFS link. Each LDAP entry contains the DFS metadata (such as targets, properties, and other information) that corresponds to that entity.
dynamic object: An object with a time-to-die (attribute msDS-Entry-Time-To-Die). The directory service garbage-collects a dynamic object immediately after its time-to-die has passed. The constructed attribute entryTTL gives a dynamic object's current time-to-live, that is, the difference between the current time and msDS-Entry-Time-To-Die. For more information, see [RFC2589].
endpoint: A network-specific address of a remote procedure call (RPC) server process for remote procedure calls. The actual name and type of the endpoint depends on the RPC protocol sequence that is being used. For example, for RPC over TCP (RPC Protocol Sequence ncacn_ip_tcp), an endpoint might be TCP port 1025. For RPC over Server Message Block (RPC Protocol Sequence ncacn_np), an endpoint might be the name of a named pipe. For more information, see [C706].
file system: A system that enables applications to store and retrieve files on storage devices. Files are placed in a hierarchical structure. The file system specifies naming conventions for files and the format for specifying the path to a file in the tree structure. Each file system consists of one or more drivers and DLLs that define the data formats and features of the file system. File systems can exist on the following storage devices: diskettes, hard disks, jukeboxes, removable optical disks, and tape backup units.
forest: One or more domains that share a common schema and trust each other transitively. An organization can have multiple forests. A forest establishes the security and administrative boundary for all the objects that reside within the domains that belong to the forest. In contrast, a domain establishes the administrative boundary for managing objects, such as users, groups, and computers. In addition, each domain has individual security policies and trust relationships with other domains.
globally unique identifier (GUID): A term used interchangeably with universally unique identifier (UUID) in Microsoft protocol technical documents (TDs). Interchanging the usage of these terms does not imply or require a specific algorithm or mechanism to generate the value. Specifically, the use of this term does not imply or require that the algorithms described in [RFC4122] or [C706] must be used for generating the GUID. See also universally unique identifier (UUID).
host name: The name of a host on a network that is used for identification and access purposes by humans and other computers on the network.
Interface Definition Language (IDL): The International Standards Organization (ISO) standard language for specifying the interface for remote procedure calls. For more information, see [C706] section 4.
Lightweight Directory Access Protocol (LDAP): The primary access protocol for Active Directory. Lightweight Directory Access Protocol (LDAP) is an industry-standard protocol, established by the Internet Engineering Task Force (IETF), which allows users to query and update information in a directory service (DS), as described in [MS-ADTS]. The Lightweight Directory Access Protocol can be either version 2 [RFC1777] or version 3 [RFC3377].
little-endian: Multiple-byte values that are byte-ordered with the least significant byte stored in the memory location with the lowest address.
member server: A server that is joined to a domain and is not acting as an Active Directory domain controller (DC). Member servers typically function as file servers, application servers, and so on and defer user authentication to the domain controller.
Microsoft Interface Definition Language (MIDL): The Microsoft implementation and extension of the OSF-DCE Interface Definition Language (IDL). MIDL can also mean the Interface Definition Language (IDL) compiler provided by Microsoft. For more information, see [MS-RPCE].
NetBIOS host name: The NetBIOS name of a host (as described in [RFC1001] section 14 and [RFC1002] section 4), with the extensions described in [MS-NBTE].
object: A set of attributes, each with its associated values. Two attributes of an object have special significance: an identifying attribute and a parent-identifying attribute. An identifying attribute is a designated single-valued attribute that appears on every object; the value of this attribute identifies the object. For the set of objects in a replica, the values of the identifying attribute are distinct. A parent-identifying attribute is a designated single-valued attribute that appears on every object; the value of this attribute identifies the object's parent. That is, this attribute contains the value of the parent's identifying attribute, or a reserved value identifying no object. For the set of objects in a replica, the values of this parent-identifying attribute define a tree with objects as vertices and child-parent references as directed edges with the child as an edge's tail and the parent as an edge's head. Note that an object is a value, not a variable; a replica is a variable. The process of adding, modifying, or deleting an object in a replica replaces the entire value of the replica with a new value. As the word replica suggests, it is often the case that two replicas contain "the same objects". In this usage, objects in two replicas are considered the same if they have the same value of the identifying attribute and if there is a process in place (replication) to converge the values of the remaining attributes. When the members of a set of replicas are considered to be the same, it is common to say "an object" as shorthand referring to the set of corresponding objects in the replicas.
object store: A system that provides the ability to create, query, modify, or apply policy to a local resource on behalf of a remote client. The object store is backed by a file system, a named pipe, or a print job that is accessed as a file.
opnum: An operation number or numeric identifier that is used to identify a specific remote procedure call (RPC) method or a method in an interface. For more information, see [C706] section 22.214.171.124 or [MS-RPCE].
primary domain controller (PDC): A domain controller (DC) designated to track changes made to the accounts of all computers on a domain. It is the only computer to receive these changes directly, and is specialized so as to ensure consistency and to eliminate the potential for conflicting entries in the Active Directory database. A domain has only one PDC.
relative distinguished name (RDN): An attribute-value pair used in the distinguished name of an object. For more information, see [RFC2251].
remote procedure call (RPC): A communication protocol used primarily between client and server. The term has three definitions that are often used interchangeably: a runtime environment providing for communication facilities between computers (the RPC runtime); a set of request-and-response message exchanges between computers (the RPC exchange); and the single message from an RPC exchange (the RPC message). For more information, see [C706].
reparse point: An attribute that can be added to a file to store a collection of user-defined data that is opaque to NTFS or ReFS. If a file that has a reparse point is opened, the open will normally fail with STATUS_REPARSE, so that the relevant file system filter driver can detect the open of a file associated with (owned by) this reparse point. At that point, each installed filter driver can check to see if it is the owner of the reparse point, and, if so, perform any special processing required for a file with that reparse point. The format of this data is understood by the application that stores the data and the file system filter that interprets the data and processes the file. For example, an encryption filter that is marked as the owner of a file's reparse point could look up the encryption key for that file. A file can have (at most) 1 reparse point associated with it. For more information, see [MS-FSCC].
RPC transport: The underlying network services used by the remote procedure call (RPC) runtime for communications between network nodes. For more information, see [C706] section 2.
Server Message Block (SMB): A protocol that is used to request file and print services from server systems over a network. The SMB protocol extends the CIFS protocol with additional security, file, and disk management support. For more information, see [CIFS] and [MS-SMB].
share: A resource offered by a Common Internet File System (CIFS) server for access by CIFS clients over the network. A share typically represents a directory tree and its included files (referred to commonly as a "disk share" or "file share") or a printer (a "print share"). If the information about the share is saved in persistent store (for example, Windows registry) and reloaded when a file server is restarted, then the share is referred to as a "sticky share". Some share names are reserved for specific functions and are referred to as special shares: IPC$, reserved for interprocess communication, ADMIN$, reserved for remote administration, and A$, B$, C$ (and other local disk names followed by a dollar sign), assigned to local disk devices.
share name: The name of a share.
site: A collection of one or more well-connected (reliable and fast) TCP/IP subnets. By defining sites (represented by site objects) an administrator can optimize both Active Directory access and Active Directory replication with respect to the physical network. When users log in, Active Directory clients find domain controllers (DCs) that are in the same site as the user, or near the same site if there is no DC in the site. See also Knowledge Consistency Checker (KCC). For more information, see [MS-ADTS].
site cost: An administrator-defined numerical value meant to indicate the bandwidth or actual monetary cost of transmitting data between two sites. Only a comparison between two site cost values is meaningful, with a lower site preferred to a higher site cost.
stand-alone DFS namespace: A DFS namespace that has DFS metadata stored locally on the host server. The path to access the DFS root or a DFS link starts with the DFS root target host name. A stand-alone DFS namespace has only one DFS root target. Stand-alone DFS roots are not fault-tolerant; when the DFS root target is unavailable, the entire DFS namespace is inaccessible. Stand-alone DFS roots can be made fault-tolerant by being created on clustered file servers.
system access control list (SACL): An access control list (ACL) that controls the generation of audit messages for attempts to access a securable object. The ability to get or set an object's SACL is controlled by a privilege typically held only by system administrators.
Unicode: A character encoding standard developed by the Unicode Consortium that represents almost all of the written languages of the world. The Unicode standard [UNICODE5.0.0/2007] provides three forms (UTF-8, UTF-16, and UTF-32) and seven schemes (UTF-8, UTF-16, UTF-16 BE, UTF-16 LE, UTF-32, UTF-32 LE, and UTF-32 BE).
Universal Naming Convention (UNC): A string format that specifies the location of a resource. For more information, see [MS-DTYP] section 2.2.57.
universally unique identifier (UUID): A 128-bit value. UUIDs can be used for multiple purposes, from tagging objects with an extremely short lifetime, to reliably identifying very persistent objects in cross-process communication such as client and server interfaces, manager entry-point vectors, and RPC objects. UUIDs are highly likely to be unique. UUIDs are also known as globally unique identifiers (GUIDs) and these terms are used interchangeably in the Microsoft protocol technical documents (TDs). Interchanging the usage of these terms does not imply or require a specific algorithm or mechanism to generate the UUID. Specifically, the use of this term does not imply or require that the algorithms described in [RFC4122] or [C706] must be used for generating the UUID.
well-known endpoint: A preassigned, network-specific, stable address for a particular client/server instance. For more information, see [C706].
MAY, SHOULD, MUST, SHOULD NOT, MUST NOT: These terms (in all caps) are used as defined in [RFC2119]. All statements of optional behavior use either MAY, SHOULD, or SHOULD NOT.