NTP

How it works

• Devices ask a trusted time server every so often and adjust their clock.
• Correct time matters for sign-in codes, certificates and security logs.
• Most devices use the maker's default time servers without any setup.
• A clock that drifts causes odd failures that are hard to trace.

What can go wrong (example scenario)

One laptop's clock had drifted several minutes. Its authenticator codes were rejected at every sign-in until the clock was corrected.

• Two-factor codes fail because a phone clock is off.
• A log review cannot line up events because two servers disagree on the time.
• A certificate looks expired because the computer thinks it is next year.

A question owners ask

Why do my codes keep failing?

Check the clock first. Codes depend on the time, and a clock that is a minute or two out can make every code fail.