NTP Explained: How It Works and What to Look For
Network Time Protocol estimates time offset and delay between clocks.
Published by Protocol Explorer · Reviewed
How NTP works
A client and server exchange timestamps. The client compares transmit and receive times to estimate round-trip delay and clock offset, then applies clock-selection and adjustment rules.
What to look for in an exchange
Examine the originate, receive and transmit timestamps and the stratum. Network asymmetry can affect the accuracy of the resulting estimate.
Follow an example step by step
- Identify the client request and server reply and the association between their timestamps.
- Compare originate, receive and transmit timestamps with the client receive time to estimate delay and offset.
- Consider server stratum and network path variability before interpreting a single sample.
Common interpretation mistake
Round-trip delay does not reveal one-way delay precisely when network paths are asymmetric.
Key point to remember
NTP clients normally use multiple samples and clock-selection logic rather than trusting one response.
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The NTP overview is free without an account. Its full interactive lesson is included in Protocol Explorer Pro, a one-time $4.99 purchase; an account is required to buy Pro and restore the licence across devices.
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Specification
Read the primary specification for NTP for the authoritative protocol details. The interactive scenario is a simplified teaching model, not a capture of your network.
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