Source: cirosantilli/cia-2010-covert-communication-websites/how-did-alexa-find-the-domains

= How did Alexa find the domains?

It can't be <HTML> crawl because presumably there wouldn't have been links to those websites? Presumably this is why <Common Crawl> doesn't seem to have any hits.

So they must have had some kind of DNS A record database?

Or would IPv4 sweep have worked, without the `Host` header with the CIA's setup?

The same question also applies to the <2013 DNS Census>. It has less hits, but still has many.

Whatever they did, we are so so glad that they did!