Glossary

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A

access control entry (ACE) An object such as a user or group that is present on an access control list.

access control list (ACL) A list of security permissions applied to an object. An ACL for an item normally includes membership (ACEs) and the actions that each member can perform on the item.

ACE See access control entry.

ACL See access control list.

Active Directory The Windows 2000 directory service, which replaces the Security Accounts Manager (SAM) in Windows NT 4. Active Directory consists of a forest, domain(s), organizational units, containers, and objects. Different classes of objects can be represented within Active Directory, including users, groups, computers, printers, and applications.

Active Directory Connector (ADC) The Active Directory Connector is a service that runs on a Windows 2000 domain controller and allows you to synchronize Exchange Server 5.5 and Windows 2000 directories. Unlike SRS, which replicates information between an Exchange 5.x organization and the configuration naming partition in Active Directory, the ADC replicates information between the Exchange 5.x directory and the domain partition in Active Directory.

ADC See Active Directory Connector.

address space The part of an e-mail address that designates the system that will receive the message. Typically, the address space is all of the address except the recipient and any delimiter. For example, in the address [e-mail], @microsoft.com is the address space.

administrative group A collection of Exchange 2000 servers that can be administered as a single unit. An administrative group can include policies, routing groups, public folder trees, monitors, servers, conferencing services, and chat networks. When security settings (permissions) are applied to an administrative group, all child objects in the tree inherit the same permissions as the administration group node.

American Standard Code for Information Interchange (ASCII) A code for representing English characters as numbers, with each letter assigned a number from 0 to 127.

ASCII See American Standard Code for Information Interchange.

automatic document property promotion A feature that allows for advanced searches on any document property, such as Author, Size, or Department. When Exchange stores a document in a supported file type, the document's properties are automatically parsed and promoted to the information store. Hence, the properties become a part of the document's record in the database. Searches can then be performed on these properties.

B

BHS See bridgehead server.

bridgehead server (BHS) A server that acts as a message transfer point between Exchange 2000 routing groups. This term also refers to a computer hosting a directory replication connector.

C

CA See certificate authority.

certificate (CA) Public keys that have been digitally signed by a trusted authority (the certificate authority) and that are used to ensure that public keys have not been tampered with. KM Server uses a certificate format that complies with the X.509 standard.

certificate authority An entity that verifies the validity of public keys that have been created for users in the organization through the issuance of certificates. The CA also issues, revokes, and renews certificates.

certificate revocation list (CRL) and
certificate trust list (CTL) Lists published by Certificate Services that name certificates whose authority can be trusted (trust list) or not trusted (revocation list).

channel See chat room.

chat community A chat entity within Exchange Server. Each administrative group in the Exchange System snap-in can have only one Chat Communities container in which multiple virtual chat communities can be created. Each chat community can host multiple chat rooms, or channels, and can be governed by its own administrative controls.

chat room A channel within a chat community. A user within a community can log on to any available chat room or even create a new one if dynamic channels are enabled for that community.

checkpoint file A file used to keep track of transactions that are committed to an Exchange database from a transaction log. Using checkpoint files ensures that transactions cannot be committed more than once.

circular logging A logging technique that involves maintaining only previous log files with uncommitted changes on the server. Fully committed transaction logs are removed to save space.

CMS See Conferencing Management Service.

Conferencing Management Service (CMS) The network service that coordinates resources for online meetings in the Exchange Conferencing Server. Each site normally has an active CMS to allow fast connection for data conferencing users.

Conferencing Server See Exchange Conferencing Server.

ConfigCA A special connection agreement implemented as part of the Active Directory Connector that replicates configuration naming partition data from Exchange 5.x sites to administrative groups in Active Directory and vice versa. ConfigCAs work in conjunction with Site Replication Service.

configuration naming partition A partition of Active Directory that stores information regarding how an Exchange 2000 system is organized. Because this information is replicated to all domain controllers in the forest, the Exchange 2000 configuration is also replicated throughout the forest. The configuration information includes the Exchange 2000 topology (such as routing group information), connectors, protocols, and service settings. See also domain naming partition and schema naming partition.

connection agreement The configuration of information to replicate using the Active Directory Connector. Configuration information includes the servers that participate in the replication, the object classes (mailbox, custom recipient, distribution list and user, contact, and group) to replicate, the containers and organizational units to use for object placement, and the activity time schedule.

contact A non-security principal that represents a user outside of the organization. A contact generally has an e-mail address, facilitating messaging between the local organization and the remote object. A contact is similar to a custom recipient in Exchange Server 5.5.

CRL See certificate revocation list.

CTL See certificate trust list.

D

DAV See Distributed Authoring and Versioning.

Digest authentication A form of authentication in Internet Information Services in which the password is sent as a hashed value that works through proxies and firewalls. This method works with all HTTP 1.1_compliant browsers, but the password is unencrypted in the Windows 2000 domain controller.

dismount See mount.

distinguished name A name assigned to every object in Active Directory that identifies where the object resides in the overall object hierarchy.

Distributed Authoring and Versioning (DAV) An extension to the Hypertext Transfer Protocol 1.1 (HTTP 1.1) that allows for the manipulation (reading and writing) of objects and attributes on a Web server. Also known as WebDAV.Exchange 2000 natively supports WebDAV. Although not specifically designed for the purpose, DAV allows for the control of data using a filing system_like protocol. DAV commands include Lock, Unlock, Propfind, and Proppatch.

DNS See Domain Name System.

domain The core unit in Active Directory. A domain is made up of a collection of computers that share a common directory database.

domain controller A Windows 2000 server that has Active Directory installed. Each domain controller is able to authenticate users for its own domain. It holds a complete replica of the domain naming partition for the domain to which it belongs and a complete replica of the configuration and schema naming partitions for the forest.

domain mode The mode in which an Active Directory domain is operating. A domain can be in either mixed mode or native mode. In mixed mode, the domain has limitations (such as 40,000 objects) imposed by the Windows NT 4 domain model. However, Windows 2000 domain controllers and Windows NT 4 backup domain controllers can coexist within the domain without problems. Switching to native mode, which is irreversible, allows the directory to scale up to millions of objects but requires that all domain controllers be upgraded to Windows 2000.

Domain Name System (DNS) A major standards-based protocol that allows clients and servers to resolve names into IP addresses and vice versa. Windows 2000 extends this concept even further by supplying a dynamic DNS (DDNS) service that enables clients and servers to automatically register themselves in the database without needing administrators to manually define records.

domain naming partition A partition of Active Directory that stores all of the domain objects for Exchange 2000 Server and replicates the objects to every domain controller in the domain. Recipient objects, including users, contacts, and groups, are stored in this partition. See also configuration naming partition and schema naming partition.

domain tree A collection of domains that have a contiguous namespace, such as microsoft.com, dog.microsoft.com, and cat.microsoft.com. Domains within the forest that do not have the same hierarchical domain name are located in a different domain tree. When different domain trees exist in a forest, it is referred to as a disjoint namespace.

DSAccess The Exchange 2000 component that provides directory lookup services for components such as SMTP, MTA, and the store. Client requests use the DSProxy service for directory access.

DSProxy The Exchange 2000 component that can proxy (and refer) MAPI directory service requests from Outlook clients to Active Directory for address book lookup and name resolution.

E

ECS See Exchange Conferencing Server.

epoxy layer See Exchange Interprocess Communication (EXIPC) layer.

ESE See Extensible Storage Engine.

event sink A piece of code that is activated by a defined trigger, such as the reception of a new message. The code is normally written in any COM-compatible programming language, such as Visual Basic, VBScript, JavaScript, C, or C++. Exchange 2000 Server supports transport, protocol, and store event sinks. Event sinks on the store can be synchronous (meaning that the code executes as the event is triggered) or asynchronous (meaning that the code executes sometime after the event).

EVS See Exchange virtual server.

Exchange Conferencing Server (ECS) A service that allows users to meet in virtual rooms on an Exchange server. ECS defines the use of a Conferencing Management Service to coordinate the room bookings and a T.120 multipoint control unit (MCU) for the actual connection of clients to a conferencing session.

Exchange Interprocess Communication (EXIPC) layer A queuing layer, formerly known as the epoxy layer, that allows the IIS and Store processes (Inetinfo.exe and Store.exe) to shuttle data back and forth very quickly. This layer is required to achieve the best possible performance between the protocols and database services on an Exchange 2000 server. Conventional applications require the processor to switch contexts when transferring data between two processes. Exchange Server 5.5 incorporates protocols such as NNTP, POP3, and IMAP directly into the Store.exe process, so data transfer is very efficient. The Exchange 2000 architecture separates the protocols from the database for ease of management and to support future architectures.

Exchange virtual server (EVS) When using clustered servers, you allocate different resources (such as storage groups) to an EVS. If a node fails, you can move an EVS from the failed node to one of the remaining nodes.

Extensible Storage Engine (ESE) A transaction logging system that ensures data integrity and consistency in the event of a system crash or media failure. Other databases, such as the Active Directory database, also use ESE.

F

failover or failback The process of moving a resource from one server in a cluster to another. Failover happens when a problem occurs on the active server and services must be transferred to the passive server.

filter rules LDAP rules created using recipient policies. Filter rules allow you to specify what kind of e-mail address is generated for each recipient object.

firewall A system designed to prevent unauthorized access to or from a private network. A firewall can be made up of hardware, software, or a combination of both. Firewalls can work by blocking certain types of packets or certain applications.

forest A collection of domains and domain trees. The implicit name of the forest is the name of the first domain installed. All domain controllers within a forest share the same configuration and schema naming partitions. To join an existing forest, you use the Dcpromo utility. The first domain within the forest cannot be removed.

front end/back end An Exchange 2000 configuration in which clients access a bank of protocol servers (the front end) for collaboration information, and these in turn communicate with the data stores on separate servers (the back end) to retrieve the physical data. A front end/back end configuration allows for a scalable single point of contact for all Exchange-related data.

G

Global Address List The list of all Exchange Server recipients in the entire Exchange organization. Exchange Server uses address lists to hold and organize the names of the recipients associated with the system.

Global Catalog server A server that holds a complete replica of the configuration and schema naming contexts for an Active Directory forest, a complete replica of the domain naming context in which the server is installed, and a partial replica of all other domains in the forest. The Global Catalog knows about every object in the forest and has representations for them in its directory, however, it may not know about all attributes (such as job title and physical address) for objects in other domains.

globally unique identifier (GUID) An attribute consisting of a 128-bit number that is guaranteed to be unique, used by applications that need to refer to an object by an identifier that remains constant. A GUID is assigned to an object when it is created, and it will never change, even if the object is moved between containers in the same domain.

group An object defined in Active Directory that contains other objects such as users, contacts, and possibly other groups. A group can be either a distribution group or a security group, and its scope can be local, domain, or universal. Groups are similar to distribution lists in Exchange Server 5.5.

GUID See globally unique identifier.

H

Heartbeat A group of packets that are sent over a private IP network between nodes to detect the health of the other nodes, as well as the health of the applications and services they manage within the cluster.

high availability A quality of a server cluster, in which ownership of resources such as disks or IP addresses is automatically transferred from a failed server to the surviving server. The software is restarted on the surviving server, and users experience only a momentary pause in service. The aim of high availability is to minimize downtime. Windows Clustering is a highly available solution, but it does not guarantee nonstop operation.

hosted organization A collection of Exchange services including but not limited to virtual servers (that is, instances of IMAP4, SMTP, POP3, NNTP, HTTP, or RVP), storage space, and real-time collaboration facilities that exist to serve the needs of a single company. A hosted organization is normally used by Internet service providers to host multiple companies on the same physical computer. However, a hosted organization is not limited to a single Exchange 2000 server.

I

IFS See Installable File System.

IIS See Internet Information Service.

IM See Instant Messaging.

IMAP4 See Internet Message Access Protocol version 4.

Installable File System (IFS) A file system that allows users to place any kind of document in the native content file (the streaming file) and then access it from almost any client, regardless of whether that client is a browser, a MAPI client, or simply Windows Explorer.

Instant Messaging (IM) The Exchange 2000 service that allows for real-time messaging and collaboration between users. Clients generally use the MSN Messenger client to log on to Instant Messaging and subscribe to other users.

Instant Messaging home server The IM server responsible for maintaining current presence information for any user assigned to it and for notifying subscribers of changes in a user's status. Messages sent to a user must first pass through the user's home server. The instant messaging client software represents the user to the home server and acts as the inbox for that user.

Instant Messaging routing server A server that either proxies Instant Messaging requests or uses HTTP to redirect the IM client to an appropriate Instant Messaging home server.

Integrated Windows Authentication A form of IIS authentication in which the password is sent as an encrypted value to highest security. This form of authentication does not work through firewalls and proxies.

Internet Information Services (IIS) Microsoft's Web server software for the Windows 2000 platform. IIS 5 ships with Windows 2000 and is installed by default during a typical Windows 2000 installation.

Internet Message Access Protocol version 4 (IMAP4) A standard-based protocol for accessing mailbox information. IMAP4 is considered to be more advanced than POP3 because it supports basic online capabilities and access to folders other than the Inbox. Exchange Server 5.x and Exchange 2000 both support IMAP4.

Internet Relay Chat (IRC) A popular chat system developed in the late 1980s that allows multiple users to participate in a chat environment at the same time. IRC is made up of an IRC server and an IRC client.

IRC See Internet Relay Chat.

K

Key Management Service (KMS) An advanced security tool in Exchange 2000 Server that protects data integrity through message encryption and digital signatures. It is an optional component of Exchange 2000 Server that works in close conjunction with Windows 2000 Certificate Services to provide a centralized public-key infrastructure.

key pair, asymmetric A pair of encryption keys that are not identical: one key is used to encrypt the data and a different key is used to decrypt it. With asymmetric keys, one key is known as the public key and the other is known as the private key. Exchange 2000 Server uses this type of encryption technology.

key pair, symmetric Identical encryption keys: both the sender and the recipient use the same key to encrypt and decrypt the data. Also known as shared keys.

KMS See Key Management Service.

L

LDAP See Lightweight Directory Access Protocol.

Lightweight Directory Access Protocol (LDAP) A standards-based protocol that can be used to interact with conformant directory services. LDAP version 2 allows users and applications to read the contents of a directory database, whereas LDAP version 3 (defined under RFC 2251) allows them to both read from and write to a directory database.

link state algorithm (LSA) The algorithm used to exchange routing status information between Exchange 2000 servers.

LSA See link state algorithm.

M

mail-based replication A mechanism to replicate directory information through a messaging transport. This term applies to Exchange 5.x intersite directory replication as well as to Active Directory replication through SMTP.

mail exchanger (MX) record A record in a DNS database that indicates a host responsible for receiving e-mail messages.

MAPI See Messaging Application Programming Interface.

Masquerade Domain option An option that allows you to indicate a different domain name to be placed in both the Mail From and From fields of all outgoing SMTP messages.

MCU See multipoint control unit.

message tracking A feature of an Exchange server that, along with the subject logging feature, provides a sophisticated way to track messages throughout the Exchange organization, primarily for troubleshooting purposes.

Message Transfer Agent (MTA) The component in all versions of Exchange Server that transfers messages between servers, using the X.400 protocol.

Messaging Application Programming Interface (MAPI) The API used by Microsoft messaging applications such as Outlook to access collaboration data. MAPI, or more specifically, MAPI RPC, is also used as the transport protocol between Outlook clients and Exchange servers.

metabase A store that contains metadata such as that used by IIS to obtain its configuration data. The metabase can be viewed through utilities such as Metaedit.

metabase update service A component in Exchange 2000 that reads data from Active Directory and transposes it into the local IIS metabase. The metabase update service allows the administrator to make remote configuration changes to virtual servers without having a permanent connection to each system.

metadata Data about data. In relation to Exchange, this term can be used in the context of Active Directory and can also be used to describe the structure within the store or the MTA.

MIME See Multipurpose Internet Mail Extensions.

mixed mode See domain mode.

mount To place an individual store in a storage group online. Stores can also be taken offline, or dismounted. You might dismount a store for maintenance, for example.

MTA See Message Transfer Agent.

multipoint control unit (MCU) A reference to the T.120 protocol, which allows clients to connect to data conferencing sessions. MCUs can communicate with each other to transfer conferencing information.

Multipurpose Internet Mail Extensions (MIME) A standard that allows multiple files of various content types to be encapsulated into one message. RFCs 2045 through 2049 currently define MIME and are considered to be one single standard.

MX record See mail exchanger (MX) record.

N

Name Service Provider Interface (NSPI) Part of the DSProxy process that can accept Outlook client directory requests and pass them to an address book provider.

namespace A logical collection of resources that can be managed as a single unit. Within Active Directory, a domain defines a namespace.

naming partition A self-contained section of a directory hierarchy that has its own properties, such as replication configuration and permissions structure. Active Directory includes the domain, configuration, and schema naming partitions.

native content file See rich text file.

native mode See domain mode.

NDR See nondelivery report.

Network News Transfer Protocol (NNTP) A standards-based protocol that includes simple command verbs to transfer Usenet messages between clients and servers as well as between servers. NNTP uses TCP/IP port 119.

NNTP See Network News Transfer Protocol.

nondelivery report (NDR) A report generated when a message is not deliverable for some reason in Exchange Server. The NDR is returned to the message sender and sometimes to an administrator or automated monitor as well.

NSPI See Name Service Provider Interface.

O

object An entity that is described by a distinct, named set of attributes. In the Windows 2000 Active Directory, all network resources are represented as objects that can be centrally administered.

OLE DB An API that allows low-level programming languages such as C and C++ to access dissimilar data stores through a common query language. OLE DB is seen as the replacement for open database connectivity (ODBC). Data stores such as those in Exchange 2000 and SQL Server allow for OLE DB access, which makes application development easier and faster.

organizational unit (OU) An Active Directory container object that is used to organize other objects within a domain. An OU can contain user accounts, printers, groups, computers, and other OUs.

OU See organizational unit.

Outlook Web Access (OWA) The Web browser interface to Exchange Server mailbox and public folder data. The OWA client in Exchange Server 5.x uses Active Server Pages to render collaboration data into HTML, whereas the OWA client in Exchange 2000 uses native access to the store.

OWA See Outlook Web Access.

P

PGP See Pretty Good Privacy.

PKI See public-key infrastructure.

policy A set of configuration parameters that applies to one or more Exchange objects in the same class. For example, you can create a policy that affects certain settings on some or all of your Exchange servers. If you ever want to change these settings, all you need to do is modify the policy and it will be applied to the appropriate server's organization.

POP3 See Post Office Protocol version 3.

Post Office Protocol version 3 (POP3) A standards-based protocol for simple access to Inbox data. All versions of Exchange server except version 4 support POP3. POP3 uses TCP/IP port 110 for client-to-server access.

Pretty Good Privacy (PGP) A public-key technique for encrypting data, developed by Philip Zimmerman. It has become a popular encryption method on the Internet because it is widely available and free.

property promotion See automatic document property promotion.

public folder A folder on an Exchange server that is part of a public store made available to multiple users. Public folder can hold messages, documents, and just about any other type of file.

public folder tree A collection of public folders created under the same hierarchical namespace. Previous versions of Exchange Server used only a single tree called All Public Folders. You can define multiple trees in Exchange 2000 Server. Each tree is a unit of hierarchy replication and can be replicated to one or more public stores. A public store can host only one tree. MAPI clients such as Outlook can access only a single tree, called All Public Folders, whereas other clients such as a Web browser, a networking client using the Microsoft Web Storage System, or any NNTP client can access any tree that is defined.

public-key infrastructure A collection of resources that work together to provide a secure network authentication system, the major components of a public key infrastructure (PKI) are certificates and certificate authorities, policies, and cryptographic service providers.

Q

Queue Viewer A tool built into the Exchange System snap-in that allows you to view any message queue. When messages are sent from an Exchange server, they are placed in a message queue, where they wait until it is their turn to go out over the appropriate connector.

quorum resource A resource that stores the cluster management data for a server cluster. It is usually held on a shared disk.

R

Recipient Update service Part of the Exchange System Attendant, this service is responsible for keeping address lists up-to-date and creating proxy addresses for users.

remote procedure calls (RPCs) A reliable synchronous protocol that allows a program on one computer to execute a program on another computer. Outlook clients use MAPI RPCs for accessing mailboxes and public folders.

resource In real-time collaboration, a user object in Active Directory that represents a facility. Outlook users use resources to book meetings and data conferences. Resources are stored in the System\Exchange organizational unit in Active Directory.

request for comments (RFC) RFCs are a series of notes about the Internet. Anyone can submit an RFC and, if an RFC gains enough support, it may become an Internet standard. Each RFC is designated by an RFC number. Once published, an RFC never changes. Modifications to an original RFC are assigned a new RFC number.

rich text file One of the two files that make up an Exchange 2000 database. The rich text file (ending in .EDB) holds mail messages and Message Application Programming Interface (MAPI) content, and the native content file or streaming file (ending in .STM) holds all non-MAPI information. The term "rich text file" is also used to describe a file formatted according to a formatting standard defined by Microsoft. RTF files are actually ASCII files with special commands embedded in them to indicate formatting.

routing group A collection of Exchange 2000 servers that can transfer messaging data to one another in a single hop without going through a bridgehead server. In general, Exchange servers within a single routing group are connected by high-bandwidth links. Connectivity among servers in a routing group is based entirely on SMTP.

Routing Group Connector A connector in Exchange 2000 Server that connects routing groups to one another. A Routing Group Connector is unidirectional and can have separate configuration properties (such as allowable message types over the connection). Routing Group Connectors use the concept of local and remote bridgeheads to dictate which servers in the routing groups can communicate over the link. The underlying message transport for a Routing Group Connector is either SMTP or RPC, and it uses link state information to route messages efficiently.

routing service A component in Exchange 2000 that builds link state information.

RPC See remote procedure calls.

S

SCC See Site Consistency Checker.

schema The metadata (data about data) that describes how objects are used within a given structure. In relation to Exchange Server, this term can be used in the context of Active Directory, but it can also be used to describe the structure within the store or the MTA.

schema naming partition A partition of Active Directory that contains all object types and their attributes that can be created in Active Directory. This information is replicated to all domain controllers in the forest. During the first installation of Exchange 2000 Server in the forest, the Active Directory schema is extended to include new object classes and attributes that are specific to Exchange 2000 Server. See also configuration naming partition and domain naming partition.

security principal A user who can log on to a domain and gain access to network resources. In Active Directory, a user object is a security principal. A non-security principal is an object represented in Active Directory that cannot access resources within the enterprise.

shared-everything architecture An architecture that gives any physical server in the cluster access to all of the data and application code at any given time and can offer these services to the client as needed. It is also known as active/active archictecture.

shared-nothing architecture An architecture that makes one of the physical nodes responsible for running an application while the other servers, or nodes, wait on the sidelines for the first physical server to fail so that they can leap into action and take over the application. Only one server works at any given time for an application. It is also known as active/passive architecture

Simple Message Transfer Protocol (SMTP) A major standards-based protocol that allows for the transfer of messages between different messaging servers. SMTP is defined under RFC 821 and uses simple command verbs to facilitate message transport over TCP/IP port 25.

single-instance storage (SIS) A storage technique in which messages sent to multiple recipients are stored only once as long as all the recipients are located in the same database. SIS is not maintained if a mailbox is moved to a different database, even if it still resides in the same storage group. Moreover, it does not span multiple databases in a single storage group.

sink See event sink.

SIS See single-instance storage.

site In Active Directory, a collection of IP subnets. All computers that are in the same site have high-speed connectivity—LAN speeds—with one another. Unlike an Exchange site, an Active Directory site does not include a unit of namespace; for example, multiple sites can exist within a single domain, and conversely, a single site can span multiple domains.

Site Consistency Checker (SCC) An updated version of the Knowledge Consistency Checker from Exchange Server 5.5. SCC runs inside the Site Replication Service. It ensures that knowledge consistency is maintained for sites and administrative groups when interoperating between Exchange Server 5.5 and Exchange 2000 Server.

Site Replication Service (SRS) The service responsible for replicating Exchange 5.x site and configuration information to the configuration naming partition of Active Directory when an Exchange 2000 server belongs to an existing Exchange 5.5 site.

SMTP See Simple Message Transfer Protocol.

SRS See Site Replication Service.

storage group A collection of Exchange databases on an Exchange 2000 server that share the same ESE instance and transaction log. Individual databases within a storage group can be mounted and dismounted. Each Exchange 2000 server can architecturally host up to 16 storage groups, although only 4 can be defined through the Exchange System snap-in.

store The generic name given to the storage subsystem on an Exchange server. This term is used interchangeably to describe the Store.exe process and Exchange databases.

sysop Short for system operator. An individual who manages an online service, such as a bulletin board or chat room.

System Attendant One of the core Exchange 2000 services. System Attendant performs miscellaneous functions (usually related to directory information), such as generating address lists, offline address books, and directory lookup facilities.

system policies General sets of rules created to apply to servers, mailbox stores, and public stores. Once a policy is created, changing the policy changes the rules for all members of that policy.

T

T.120 A standards-based protocol used with Exchange Conferencing Server. Clients such as Microsoft NetMeeting are T.120 compatible.

TCP port In the TCP/IP protocol, a TCP port identifies a logical connection that an application can use to transport data. For example, port 80 is normally used to send HTTP messages.

transaction logs The primary storage area for new transactions made to ESE databases. Data is written to these logs sequentially as transactions occur. Regular database maintenance routines then commit changes in the logs to the actual databases.

U

UPN See user principal name.

user In Active Directory, a security principal (a user who can log on to the domain). A user may have an e-mail address and/or an Exchange mailbox, making the object mail enabled and/or mailbox enabled, respectively.

user ban An action that prevents an individual user from accessing a specific chat community. If that user attempts to access a banned community, he or she is refused. The user can be restricted by nickname, user name, or both.

user principal name (UPN) A name that is generated for each object, in the form username@domainname. A UPN allows the underlying domain structure and complexity to be hidden from users. For example, although many domains may exist within a forest, users would seamlessly log on as if they were in the same domain.

V

virtual root A shortcut pointer to a physical storage location. Virtual roots are normally defined to allow users and applications to connect with a short "friendly" path instead of navigating a complex hierarchy. IIS uses the concept of virtual roots to expose resources provided by a Web server.

virtual server An instance of any service type normally implemented in IIS. For example, a virtual server can be an instance of FTP, IMAP, Instant Messaging, HTTP, NNTP, POP3, or SMTP. An Exchange 2000 server can host multiple virtual servers of the same type on each computer. Each virtual server can have its own configuration properties, such as bound IP addresses, port number, and authentication type.

W

WebDAV See Distributed Authoring and Versioning.

Web Store The database architecture in Exchange 2000. Previous releases of Exchange exposed data such as public folders only through MAPI, whereas Exchange 2000 exposes all of its data through MAPI, HTTP, and Win32 layers. This means that an object stored in a public folder can be retrieved and manipulated through a Web browser or a standard client with a network redirector. The Exchange 2000 store exposes itself to the operating system as an Installable File System, which means that the underlying data can be accessed through a drive letter and, in turn, that this drive and its folders can be shared via a universal naming convention (UNC) path to allow other clients to connect to the data.

X

X.400 A messaging standard that can be used by many messaging systems. X.400 uses a strict addressing method that reflects a hierarchical environment. An X.400 address reflects the recipient's position in a messaging hierarchy.

X.400 Connector A connector that can be used to connect an Exchange system to a foreign X.400 system or to connect two Exchange routing groups over unstable or low-bandwidth (typically less than 16 Kbps) connections.

X.500 A standard that defines how directories should be structured. X.500 directories are hierarchical, with different levels for each category of information. Both Active Directory and LDAP are loosely based on the X.500 standard.

X.509 A standard that defines digital certificates.