Detecting Unknown Subdomains with Certificate Transparency — A Practical Introduction Using Cert Spotter

A practical guide to detecting new subdomains and SSL/TLS certificates issued under a root domain you own, from the outside. It walks through Certificate Transparency (CT) log fundamentals, subdomain discovery and continuous monitoring with the Cert Spotter API and crt.sh, the blind spots created by wildcard certificates and wildcard DNS, and a recommended layered setup that combines CT with Passive DNS.

How to Fix 'This site can't be reached DNS_PROBE_FINISHED_NXDOMAIN' in Chrome Browser

Four things I tried on macOS Chrome to clear the DNS_PROBE_FINISHED_NXDOMAIN error.

Collection of Articles That Help Understand DNS Propagation

A short link collection of articles that explain how DNS propagation works.

Domain Transfer from Onamae.com to Cloudflare Registrar

A walkthrough of transferring a domain from Onamae.com to Cloudflare Registrar to reduce renewal costs.

Migrating Domain Registrar from DNSimple to Amazon Route 53

Steps for migrating a domain registrar from DNSimple to Amazon Route 53.

[Tumblr] How to Set Up a Custom Domain

Setting up a custom domain on Tumblr, and what I did when the domain test kept failing at first.

VALUE-DOMAIN DNS Settings Not Reflecting Due to Unconfigured Name Servers

How to fix VALUE-DOMAIN DNS not reflecting by configuring the name servers to ns*.value-domain.com.