[sandeepkd]

Yes CT is explicitly stated source which is why I qualified it with "Guess" for domain registration. There were couple reasons for that -

1. Quite a few websites in the search results where just on HTTP

2. The .gov sites do use public certificate authorities like digicert, verisign, amazon & letencrypt so they would have been captured unless they are removed explicitly

And yes the domain registration would not include subdomains

[marysol5]

.gov.uk plenty of them use standard CA's

manchester.gov.uk uses LE