One place I interviewed for actually wanted to see my physical diploma. This was memorable bc it was the only time it ever happened and luckily I happened to know where it was. Usually yeah they just contact the university's "registrar" or "academic records" office and as part of the application process you sign a form saying it's OK to release your records to them.

As well as employers contacting the university for verification, graduates can request their university send certified copies of their transcripts and diplomas. It's also possible for candidates to supply an unofficial transcript that can be later verified.

The context of the thread is few employers seem to question if educations are legitimate, not that they suspect they're fake. The point I'm making is that not only are they not verifying information with my university, they're not even asking me to substantiate anything, official or otherwise.