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This article is a rough explanation of the Network Time Protocol.

Everything might be not exactly correct in this article but it’s very useful for beginners to understand IT terms. If you want to learn IT but you don’t have any experience to work in the IT industry, I wish it helps you to understand IT. And I hope this article makes you study IT more.

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What is the Network Time Protocol?

The Network Time Protocol is a network protocol.
NTP is the abbreviation for the Network Time Protocol.
NTP is one of the oldest Internet protocols in current use.
NTP is a protocol for synchronizing the clock between the client and the server.

1. Network Time Protocol

The Network Time Protocol is the rule on how to synchronize the clock between the client and the server. It serves as the adjustment to the delay. Implementations send and receive timestamps using the User Datagram Protocol (UDP) on port number 123. This protocol is used in layer 7 of the OSI model.

There are servers and clients.

The NTP servers receive accurate Coordinated Universal Time(UTC) from an authoritative clock source, such as an atomic clock and GPS. The NTP clients request and receive time from NTP servers.

2. Why is NTP important?

Network management:

When several systems work together to process on the same service, they must use the same clock for reference to ensure correct sequencing of operations. They must be performed based on time. If their system time is different, problems could occur, such as automatic updates, executes patches, and referring log files.

What is a log?: IT Learning | IT Terms | Log | Japan Teams

Payment system:

Online payment services must know the time accurately and require consistent time on all devices. If these requirements are not met, inaccurate payments will occur.

3. NTP stratum

NTP uses a hierarchical, semi-layered system of time sources.

Each level of this hierarchy is termed a stratum and is assigned a number starting with zero. A server synchronized to a stratum n server runs at stratum n+1.

The number represents the distance from the reference clock. And it is used to prevent cyclical dependencies in the hierarchy.

Stratum 0

There are high-precision timekeeping devices, such as atomic clocks, GPS, or radio clocks. Stratum 0 devices are also known as reference clocks. NTP servers cannot advertise themselves as stratum 0.

Stratum 1

NTP servers of Stratum 1 are synchronized within a few microseconds of their attached stratum 0 devices(Computers in Stratum 1 are attached directly to clocks in Stratum 0). These servers are referred to as primary time servers.

Stratum 2

These are computers that are synchronized over a network to stratum 1 servers.

A stratum 2 computer queries several stratum 1 servers. Stratum 2 computers may also peer with other computers in stratum 2 to provide a more stable time for all devices in the peer group.