Technical notes

Field notes

A few small details worth getting right.

404 is a useful response

An unknown URL should generally return an actual 404 Not Found, not a successful response containing an unrelated home page. Correct status codes make monitoring, caching and debugging much easier.

---

Certificate renewal is not the last step

ACME clients can renew certificates automatically, but the process using them also needs to pick up the updated files. A renewal test and a reload check belong in the same maintenance routine.

---

Don't confuse DNS with connectivity

A name resolving correctly proves only that a resolver returned an address. It says nothing about whether a TCP connection succeeds, whether TLS validates or whether the application returns the expected content.

---

Cache deliberately

Versioned CSS and image assets can often be cached longer than HTML documents. Headers such as Cache-Control, ETag and Last-Modified provide useful control over repeat requests.