Jan, 28 2022

Tools

Network Time Protocol (NTP) Tester

Test an NTP server to determine if it is working as expected.

Frequently Asked Questions

NTP is the abbreviation of Network Time Protocol. It is a networking protocol that synchronizes the clock between computer systems to the same time reference. It was designed by David L. Mills back in 1985, which makes it the oldest protocol in use. NTP synchronizes all the computers in a network to be within the same coordinated universal time. Its design leverages accurate time servers to mitigate the variable network latency effects.
Time never stops; it just advances. NTP uses an intersection algorithm to pick accurate time servers and synchronize all the participating computers. It maintains time to within a few milliseconds under ideal conditions. Due to network latency, computers need to follow coordinated time for the applications to work effectively. NTP receives accurate time from the reference clock, and then it calculates additional statistical values to improve time.
An NTP server acts as the reference for accurate time to all connected computers. The clients send a time request to the NTP server, then calculates the link delay to get accurate results. The server is always connected to a GPS to ensure that all the clients maintain accurate time. The clients can also send manual requests to the SNTP. They are primarily used in distributed systems, but you can also use them in a peer-to-peer network.

Common NTP servers?

Google Public NTP:
time.google.com
time1.google.com
time2.google.com
time3.google.com
time4.google.com

Facebook NTP:
time.facebook.com
time1.facebook.com
time2.facebook.com
time3.facebook.com
time4.facebook.com
time5.facebook.com

Apple NTP server:
time.apple.com
time.euro.apple.com

Microsoft NTP server:
time.windows.com

Microsoft NTP server:
time.windows.com
You can use any public NTP server for your projects. However, we highly recommend using the most common servers. If you use a leap smearing NTP, you should not combine it with other servers. This will ensure that your system receives accurate time throughout. Use an NTP that conforms to your system.

About time.google.com?

Time.google.com is a public NTP developed by Google. It is a unique NTP since it uses the leap smearing technique to handle leap seconds. Google has implemented this technique with a fleet of clocks and load balancers in their data centers. Anyone can use the time.goog.com server. However, Google recommends configuring it with only leap-smearing NTP servers.
Leap smearing refers to a technique used to smear time over a given period to account for the leap seconds. A leap second is a one-second addition to the coordinated universal time that matches the difference between the observed solar time and the precise time measured by a clock. The observed universal time (UT1) varies because of the slumping down of the earth's rotation. Leap smearing helps software code and IT systems to interact with others smoothly.

How to check NTP on Linux? (ntpdate -q)

You can check NTP on Linux by running the ntpdate -q command on the terminal. Ntpdate command syncs local time to the global NTP server. But ntpdate -q stands for query only; it does not set the clock. Alternatively, you can query the remote server by using sntp. –q terminates the command if time is already configured.

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