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#ntp

2 stories

Banner: some users' two-factor codes always failed because server clock drift in one container broke TOTP

Web Development Bug Report

Some users' two-factor codes always failed: server clock drift in one container broke TOTP

Rafael Domínguez · Jun 23, 2025 · 7 min read

A small share of users reported that their authenticator codes were rejected, but only sometimes. One application server's clock ran 70 seconds behind, so codes failed whenever a login reached it. How we found it, fixed time sync, and kept a tight verification window with replay protection.

Banner: Binance API rejecting signed requests because the client clock drifted

Networking & DNS Bug Report

Binance API -1021: Timestamp for this request is outside of the recvWindow

Ryan Pham · Oct 9, 2024 · 5 min read

Our trading bot's signed requests started failing with error -1021 a few times an hour, then constantly. The VM's clock had drifted almost two seconds because time sync was not running. Fixing NTP, measuring the offset against server time and handling -1021 explicitly ended it.