Step-by-step
technical guides

Complete guide to DNS propagation — what it is, why it takes hours and how to check when it's done.

Explanation of reverse DNS (PTR record) — why it matters for email delivery, how to configure it and how to check it.

What information a domain WHOIS contains, what each field means and how to check expiry, registrar and nameservers.

Guide to DNSSEC — how DNS records are signed, what DS/DNSKEY/RRSIG are and how to verify your domain is correctly configured.

Methodical approach to finding and fixing DNS problems — from NS delegation to MX misconfigurations.

Step-by-step guide to SPF, DKIM and DMARC — email authentication so your emails stop going to spam.

Main reasons emails go to spam — SPF/DKIM/DMARC errors, blacklisted IP, content triggers — and how to fix each one.

Guide to email headers — how to trace the path, check SPF/DKIM/DMARC results and identify spam indicators.

Guide to SSL certificates — what to check, how to read the chain, common errors and how to avoid expiry.

Complete guide to HTTP security headers — HSTS, CSP, X-Frame-Options, Referrer-Policy — what each one does and how to add them to your server.

Guide to HTTP redirects — difference between 301/302/307/308, how chains affect SEO and speed, and how to detect redirect loops.

How robots.txt works, what Allow/Disallow rules mean, and what the new llms.txt is for controlling AI crawlers.

Complete guide to JSON — syntax, common errors, formatting, minifying and converting to plain text.

What Base64 is and when to use it, how URL encoding works and what Punycode is for international domain names.

When to scan a file, how to read VirusTotal results, what false positives are and what to do when a threat is found.

What technology fingerprinting is, how CMS, frameworks, server and CDN are detected from headers/cookies/HTML, and how to read the results correctly.