S

schema

In Active Directory, a description of object classes and attributes that the object class must possess and can possess.

schema naming partition

This contains information about all the object classes and their attributes that can be stored in Active Directory.

security group

A Microsoft Windows Server 2003 Active Directory group type that can be used for assigning permissions to resources and can be mail-enabled and used as a distribution list.

security identifier (SID)

A unique identifier associated with every Active Directory user account and security group. SIDs are never reused, so if an account is deleted and then recreated with the exact same name and information, it is seen as an entirely new object to Active Directory.

service account

A special account created for use by an application's services. Service accounts are used when specific security contexts are needed that you don't want to grant to an existing user account (such as the Administrator account), and you want to be able to specify account settings that will not be subject to domain policies.

service dependency

Services often rely on other services running in order to be able to run. If a service that has a number of dependencies is stopped, intentionally or not, all dependent services will also stop.

SID

See security identifier (SID).

Simple Message Transfer Protocol (SMTP)

The native transport protocol of Microsoft Exchange Server 2003, SMTP is a standards-based protocol that allows for the transfer of messages between different messaging servers. SMTP is defined under Request for Comment (RFC) 821 and uses simple command verbs to facilitate message transport over TCP/IP port 25.

Single Instance Storage (SIS)

A feature of Microsoft Exchange Server 2003 that reduces the overall size of an information store by creating only one instance of a message and using pointers to refer multiple users back to it. If a message sent to a distribution list is deleted by one user, only the pointer is deleted for that user. The message itself is not deleted until the last user's pointer is removed.

SIS

See Single Instance Storage (SIS).

site

A well-connected Transmission Control Protocol/Internet Protocol (TCP/IP) subnet. The term site refers either to a grouping of Active Directory servers or to a grouping of Microsoft Exchange Server 5.5 servers. With Microsoft Exchange Server 2003, sites are divided into administrative groups and routing groups.

Site Replication Service (SRS)

Works in conjunction with Active Directory Connector to provide replication services from Active Directory to the Exchange 5.0 Directory Service and Exchange 5.5 Directory Service.

source domain and target domain

When you use either the Active Directory Migration Tool or the Migration Wizard, you define a source domain that contains the accounts and mailboxes you are migrating and a target domain that is the destination for the migration.

SRS

See Site Replication Service (SRS).

storage group

A collection of mailbox stores and public folder stores that share a set of transaction log files. Microsoft Exchange Server 2003, Enterprise Edition, supports up to four storage groups per server, and each storage group can contain up to five stores.

store

Implemented using the Extensible Storage Engine (ESE), a store is a database that can be for storing either mailbox information (mailbox stores) or public folders (public stores). Stores are contained within storage groups, and a single storage group can hold up to five stores.

subnet

A collection of hosts on a network that are not separated by routers. A basic corporate local area network (LAN) with one location would be referred to as a subnet when it is connected by a router to another network, such as that of an Internet service provider.

System Attendant

One of the core Microsoft Exchange Server 2003 services, the System Attendant performs various functions such as generating address lists, offline address books, and directory lookup facilities. The System Attendant must be running before other key services, such as the Information Store and the Directory Service, can start.

system policies

Sets of rules configured to apply to servers, mailbox stores, and public folder stores.