Transmission Control Protocol (TCP) is one of the core protocols of the Internet Protocol Suite. TCP is so central that the entire suite is often referred to as "TCP/IP." Whereas IP handles lower-level transmissions from computer to computer as a message makes its way across the Internet, TCP operates at a higher level, concerned only with the two end systems, for example a Web browser and a Web server. In particular, TCP provides reliable, ordered delivery of a stream of bytes from one program on one computer to another program on another computer.

Point-to-Point Protocol, or PPP, is a data link protocol commonly used to establish a direct connection between two networking nodes. It can provide connection authentication and can also provide transmission encryption privacy and compression.

DCL language is used to control access to data in a database.This language defines the access permissions for users and groups on the pieces of data in database.E.g We use commands to provide permissions for individual user to make SELECT statements for data table.

Examples of DCL commands include:

•     GRANT to allow specified users to perform specified tasks.
•     REVOKE to cancel previously granted or denied permissions.

The following privileges can be GRANTED TO or REVOKED FROM a user or role: