Network Time Protocol (NTP)

NTP uses the TCP transport protocol and is the protocol that facilitates the communication of time information between systems. The idea is that one system configured as a time provider transmits time information to other systems that can be both the time receivers and the time providers to other systems.

Network News Transport Protocol (NNTP)

The Network News Transfer Protocol (NNTP) is a protocol associated with posting and retrieving messages from newsgroups. A newsgroup is the name given to a discussion forum that is hosted on a remote system. By using NNTP client software, similar to that included with many common email clients, users can post, reply, and retrieve messages.

NNTP is an application layer protocol that uses TCP as its transport mechanism.

Secure Copy Protocol (SCP)

The Secure Copy Protocol (SCP) is another protocol based on Secure Shell (SSH) technology.

SCP provides a secure means to copy files between systems on a network. By using SSH technology, it encrypts data as it travels across the network, thereby securing it from eavesdropping.

It is intended as a more secure substitute for the Remote Copy Protocol (RCP). SCP is most commonly associated with UNIX or Linux platforms, though it is available as a command-line utility or as part of application software for most commonly used computing platforms. SCP operates at the application layer of the OSI model.