A practical guide to DNS resolution: how queries flow, what each record type does, and why "propagation" isn't really propagation.
August 23, 2026Field notes for the toolkit
Practitioner-level guides on DNS, IPs, email deliverability, TLS, and HTTP — from the engineers who built the tools.
Most email deliverability problems are about authentication and reputation, not content. Here's the practical playbook for SPF, DKIM, DMARC, and PTR.
August 23, 2026A practical guide to TLS certificates: SANs, chains, validity windows, OCSP stapling, and the errors you'll actually see in browsers.
August 23, 2026A clear-eyed explainer of what an IP address actually exposes: ISP, ASN, approximate location, and the limits of geolocation, plus how VPNs and IPv6 change the...
August 23, 2026A practical tour of DNS lookups, the four common ways DNS breaks in production, and the fastest tools to find which one bit you.
August 23, 2026A reading-guide for the “What is My IP” answer — what the number actually represents and what to check next.
August 23, 2026How DNS propagation actually works, why it's entirely a caching phenomenon, and how to flush a TTL the right way.
August 23, 2026Three numbers, four interpretations. A practical guide to reading bandwidth, ping, and jitter from any speed test.
August 23, 2026How RBLs work, why your sending IP is on one, and how to get off.
August 23, 2026IPv4 vs IPv6 explained in practical terms. When each one matters, and where you still need both.
August 23, 2026What an MX record is, how priorities work, and the four ways MX setups break in practice.
August 23, 2026A field-by-field tour of a TLS certificate and what each one means in practice.
August 23, 2026The ten DNS record types every developer should know, what each does, and the gotchas.
August 23, 2026A step-by-step setup guide for connecting a new domain to a host, plus the five DNS records every site needs.
August 23, 2026Five HTTP headers worth reading on every site, what they mean, and what their absence signals.
August 23, 2026How reverse DNS works, what FCrDNS is, and why mail bounces without it.
August 23, 2026What WHOIS still exposes after GDPR + privacy services, and how to read the remaining trust signals.
August 23, 2026