S

SCC

See Site Consistency Checker (SCC).

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 Server 2003 in the forest, the Active Directory schema is extended to include new object classes and attributes that are specific to Exchange Server 2003. See also configuration naming partition and domain naming partition.

security policy

See information security policy and electronic security policy.

security principal

An Active Directory object, such as a user or group, that defines a security context. 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 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 architecture.

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 widely used 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 when a mailbox is moved to a different database, even if that mailbox still resides in the same storage group. Moreover, SIS does not span multiple databases in a single storage group.

sink

See event sink.

SIS

See single-instance storage (SIS).

site

In Active Directory, a collection of IP subnets. All computers 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 Server 2003.

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 server belongs to an existing Exchange 5.5 site.

SMTP

See Simple Message Transfer Protocol (SMTP).

SRS

See Site Replication Service (SRS).

storage group

A collection of Exchange databases on an Exchange server that share the same ESE instance and transaction log. Individual databases within a storage group can be mounted and dismounted.

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 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.