Network Time Protocol

The Network Time Protocol (NTP) is a protocol for distributing the Coordinated Universal Time (UTC) by synchronizing the clocks of computer systems over IP networks.

NTP is one of the oldest Internet Protocols still in use (since before 1985) and uses UDP port 123.

References

• Mills, David L. Computer Network Time Synchronization: The Network Time Protocol. Taylor & Francis / CRC Press. ISBN 0849358051.

Other websites

• NTP Public Services Project This is the home for the NTP (Network Time Protocol) Public Services Project which provides public support for the NTP Project and the IETF NTP Working Group. Also a Wiki with lists of NTP servers.
• IETF NTP working group
• David Mills' NTP project page
• NTP version 4 Release Notes
• Time and NTP paper
• NTP Articles and News - A collection of NTP related articles and news
• NTP Survey 2005
• Network Time Protocol - National Research Council of Canada
• Online NTP Test Utility - Tests a NTP Server which is public to the internet
• A Brief Guide to NTP - Google Knol on NTP
• Time Synchronisation Blog

Other time synchronization protocols

• Daytime protocol DAYTIME synchronization protocol via TCP or UDP port 13
• ICMP protocol Time synchronization with ICMP timestamps (basis for timed )
• HTTP Time Protocol (HTP) Time synchronization with HTTP headers
• Reference-Broadcast Synchronization (RBS) Time synchronization for wireless networks
• Time protocol Time synchronization protocol via TCP or UDP port 37