Diagnostic suite · live
Guides
Long-form, plain-English write-ups on DNS, email deliverability, TLS and domain infrastructure. Written by engineers who got tired of copying from Stack Overflow.
DNS9 min read
How DNS propagation actually works
TTL, resolver caches, and why '24-48 hours' is usually a myth.
DNS10 min read
DNSSEC — the chain of trust for DNS
How DNSSEC signs records, what DS and DNSKEY do, and the operational risks.
Email9 min read
MX records — how email finds your servers
Priority, fallback, null MX and the patterns real email teams use.
Email10 min read
SPF explained — writing a strict record
The 10-lookup trap and a production-safe rollout template.
Email9 min read
DKIM signing, selectors and key rotation
What DKIM signs and the zero-downtime rotation pattern.
Email11 min read
DMARC in plain English
p=none vs quarantine vs reject and the safe rollout path.
Security10 min read
SSL/TLS certificates in 2026
Chains, short-lived certs and the deployment patterns that don't break.
Domain9 min read
WHOIS and RDAP — what you can still find
Ownership, privacy and GDPR — reading a modern domain lookup.
More guides shipping regularly — track updates in the changelog.