https://www.xbcatm.com/tags/operations/Illustrated field notes on HTTP, DNS, TLS, Caddy, SSH, releases, and recovery.Hugoen-ushttps://www.xbcatm.com/notes/backups-are-only-useful-after-a-restore-rehearsal/Sat, 22 Aug 2026 00:00:00 +0000https://www.xbcatm.com/notes/backups-are-only-useful-after-a-restore-rehearsal/A backup plan should prove that the important files can be found, verified, and restored.https://www.xbcatm.com/notes/dns-changes-need-a-cache-aware-rollback-window/Sat, 22 Aug 2026 00:00:00 +0000https://www.xbcatm.com/notes/dns-changes-need-a-cache-aware-rollback-window/Lowering a TTL just before a change does not remove answers already cached with the old value.https://www.xbcatm.com/notes/redirects-and-error-codes-should-preserve-the-story/Sat, 22 Aug 2026 00:00:00 +0000https://www.xbcatm.com/notes/redirects-and-error-codes-should-preserve-the-story/Use permanent redirects and absence codes to describe what happened, not to hide a broken route.https://www.xbcatm.com/notes/reliable-defaults-beat-clever-recovery/Sat, 22 Aug 2026 00:00:00 +0000https://www.xbcatm.com/notes/reliable-defaults-beat-clever-recovery/A predictable first path prevents more incidents than a complicated fallback can repair.https://www.xbcatm.com/notes/restart-policies-need-a-rate-limit/Sat, 22 Aug 2026 00:00:00 +0000https://www.xbcatm.com/notes/restart-policies-need-a-rate-limit/Let systemd recover transient failures without hiding a permanent configuration error.https://www.xbcatm.com/notes/robots.txt-and-sitemaps-answer-different-questions/Sat, 22 Aug 2026 00:00:00 +0000https://www.xbcatm.com/notes/robots.txt-and-sitemaps-answer-different-questions/Keep crawler preferences, URL discovery, and access control separate.https://www.xbcatm.com/notes/ssh-host-keys-are-part-of-the-deployment-record/Sat, 22 Aug 2026 00:00:00 +0000https://www.xbcatm.com/notes/ssh-host-keys-are-part-of-the-deployment-record/Keep first contact explicit and reject unexpected host-key changes.https://www.xbcatm.com/notes/the-advantage-of-small-systems/Sat, 22 Aug 2026 00:00:00 +0000https://www.xbcatm.com/notes/the-advantage-of-small-systems/A system is easier to trust when its important behavior fits inside a single mental model.