DNS trivia with consequences: strings.ToLower can change which host you resolve. Turkish İSTANBUL, fullwidth letters, and the Kelvin sign all fold to different DNS names, so nurago's dnscache folds ASCII only, per RFC 4343. Then the dial path: dedupe by parsed address and interleave IPv6 with IPv4, so one dead family costs one bounded attempt. https://tecnick.com/articles/nurago-dnscache/ #golang