[meigwilym]

I think the first one is pretty likely.

OP, you can search for "site:getexample.com" which will list you any pages that have been indexed for that domain. They might have just redirected the homepage. Worth a shot.

[timewizard]

I would expect the certificate mismatch to prevent this.

[maltelandwehr]

The certificate mismatch does not play any role in this SEO tactic. It just is not a factor.

[timewizard]

I was thinking of CNAMEs.