Something is wrong? Start at the top and stop when the evidence disagrees with your theory. These ten describe where to look and what a healthy answer looks like.
Read the public edge in two commands When something looks wrong, read the edge before guessing.
A release is not complete until the public edge agrees Prove the release from the outside without changing state.
Validators decide whether a cached copy is still the answer Validators decide whether a cached copy is still the answer.
Range requests should prove which bytes were selected Prove which bytes a range request actually selected.
HEAD should describe the same representation as GET Compare HEAD metadata with GET for the same selected representation; HEAD has no response body, and some generated headers may be omitted.
A certificate chain is a path you should be able to print Print the chain the visitor actually receives.
Certificate expiry is a date, not a dashboard color Expiry is a date; check it before the dashboard turns red.
DNS changes need a cache-aware rollback window Change DNS with a cache-aware rollback window.
A postmortem should leave a fact record After the incident, leave facts instead of narratives.
Backups are only useful after a restore rehearsal A backup nobody restored is only hope.
Next: Audit the trust of a public edge
Sources
- RFC 9110 — HTTP Semantics, method, status, and validator semantics used in this troubleshooting path, checked 2026-09-05.
- Caddy Documentation, static-server behavior relevant to edge troubleshooting, checked 2026-09-05.
- MDN: HTTP, practical HTTP reference for the troubleshooting path, checked 2026-09-05.