Question 1

What is subdomain takeover?

Accepted Answer

Subdomain takeover occurs when a subdomain's DNS record (usually a CNAME) points to a third-party service (GitHub Pages, Heroku, Fastly) that has been deprovisioned. An attacker can claim that service and serve content under your subdomain, potentially stealing cookies or credentials. Dangling CNAMEs are the most common vector.

Question 2

What is Certificate Transparency?

Accepted Answer

Certificate Transparency (CT) is an open framework where Certificate Authorities are required to log every SSL certificate they issue to public CT logs. This allows domain owners, researchers, and security tools to audit all certificates issued for a domain, including subdomains that may not be publicly known.

Question 3

Are all subdomains found by this tool?

Accepted Answer

This tool finds subdomains that have been secured with SSL certificates (logged in CT logs). Internal-only subdomains not secured with a public SSL cert will not appear. For comprehensive enumeration, combine CT log mining with DNS bruteforce and OSINT techniques.