Reference
Reference library
The things you look up repeatedly, written out once, with the caveats that the official documentation leaves to experience. Every code block here is meant to be pasted and then read.
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Protocol · 8 min
HTTP status codes
Every HTTP status code a webmaster meets, what it means, and how crawlers treat it — including the difference between 404 and 410, why 302 loses signals, and when 503 is the right answer.
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Security · 9 min
Security headers
The nine HTTP security headers worth sending, recommended values, the nginx block to paste, which headers are now obsolete, and the add_header inheritance trap that silently drops them.
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Performance · 9 min
Cache headers
Cache-Control directives explained, the right policy for HTML against fingerprinted assets, ETag and Last-Modified validators, how Vary destroys CDN hit rates, and working nginx configuration.
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Infrastructure · 10 min
DNS record types
Every DNS record type a webmaster sets, why a CNAME cannot sit at the apex, how TTLs really govern a migration, the full mail-authentication record set, and the dig commands to verify it.
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Servers · 11 min
nginx recipes
Tested nginx blocks for single-hop canonical redirects, compression, asset caching, reverse proxying, rate limiting, honest 404s and per-vhost logging — plus why a passing nginx -t can still break your site.
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Performance · 9 min
Core Web Vitals
LCP, INP and CLS thresholds, how to break LCP into its four phases, why INP is a main-thread problem, what causes layout shift, and why lab scores disagree with Search Console.
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Process · 7 min
Launch checklist
What to verify before DNS points at a new site, in the first hour after launch, and in the first week — including the three mistakes that cause the most damage and why each is easy to miss.