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.
Step-by-step resolution for Google & Yahoo bulk sender requirements and alignment.
Configure HSTS, CSP, X-Frame-Options & Permissions-Policy for an A+ score.
A vs AAAA, CNAME flattening, MX priority, TXT records, and CAA constraints.
Calculate IP subnet ranges, masks, and architect multi-AZ cloud VPCs.
RFC 6962, Merkle audit trees, passive subdomain discovery and SSL monitoring.
TTL, resolver caches, and why '24-48 hours' is usually a myth.
How DNSSEC signs records, what DS and DNSKEY do, and the operational risks.
Priority, fallback, null MX and the patterns real email teams use.
The 10-lookup trap and a production-safe rollout template.
What DKIM signs and the zero-downtime rotation pattern.
p=none vs quarantine vs reject and the safe rollout path.
Chains, short-lived certs and the deployment patterns that don't break.
Ownership, privacy and GDPR — reading a modern domain lookup.