Discover from certificate records
Passive discovery fetches concrete hosts visible in public certificate transparency data. This is not a full DNS zone export; hosts without certificates may not appear.
See source and timing
Source and first and last seen times are stored. If a source fails, previous inventory is kept and the partial result is marked.
Limited web checks
A limited number of discovered hosts are checked for HTTP or HTTPS response. This does not mean every subdomain is continuously monitored.