T

target

The mapping destination of a DFS root or link, which corresponds to a physical folder that has been shared on the network. See also DFS root; Distributed File System (DFS).

Time to Live (TTL)

For Internet Protocol (IP), a field in the IP header of an IP packet that indicates the maximum number of links over which the packet can travel before being discarded by a router.

For DNS, TTL values are used in resource records within a zone to determine how long requesting clients should cache and use this information when it appears in a query response answered by a DNS server for the zone.

See also DNS server; Domain Name System (DNS); Internet Protocol (IP); packet; Transmission Control Protocol/Internet Protocol (TCP/IP); zone.

topology

The physical layout of computers, cables, switches, routers, and other components of a network. Topology also refers to the underlying network architecture, such as Ethernet or Token Ring.

In Active Directory replication, the set of connections that domain controllers use to replicate information among themselves .

See also Active Directory replication; domain controller.

Transmission Control Protocol/Internet Protocol (TCP/IP)

A set of networking protocols widely used on the Internet that provides communications across interconnected networks of computers with diverse hardware architectures and various operating systems. TCP/IP includes standards for how computers communicate and conventions for connecting networks and routing traffic. See also Internet Protocol (IP); protocol.

trust relationship

A logical relationship established between domains to allow pass- through authentication, in which a trusting domain honors the logon authentications of a trusted domain. User accounts and global groups defined in a trusted domain can be given rights and permissions in a trusting domain, even though the user accounts or groups don t exist in the trusting domain s directory. See also domain; global group; group ; permission; user account.

tunnel

A logical connection over which data is encapsulated. Typically, both encapsulation and encryption are performed, and the tunnel is a private, secure link between a remote user or host and a private network. See also host.