T

Telnet

A protocol that enables an Internet user to log on to and enter commands on a remote computer linked to the Internet, as if the user were using a text-based terminal directly attached to that computer. Telnet is part of the TCP/IP suite of protocols. The term telnet also refers to the software (client or server component) that implements this protocol.

See also Transmission Control Protocol/Internet Protocol (TCP/IP).

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 Domain Name System (DNS).

See also Internet Protocol (IP).

See also packet.

See also Transmission Control Protocol/Internet Protocol (TCP/IP).

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).

Transport Layer Security (TLS)

A standard protocol that is used to provide secure Web communications on the Internet or intranets. It enables clients to authenticate servers or, optionally, servers to authenticate clients. It also provides a secure channel by encrypting communications. TLS is the latest and a more secure version of the SSL protocol.

See also authentication.

Trivial File Transfer Protocol (TFTP)

A protocol used to download the initial files needed to begin the installation process.

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 authentication.

See also domain.

See also group.

See also 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 encryption.

two-way trust

A trust relationship between two domains in which both domains trust each other. For example, domain A trusts domain B, and domain B trusts domain A. All parent-child trusts are two-way.

See also domain.

See also trust relationship.