Their other domains:
https://sci-hub.cc (uses sci-hub.io certificate)
https://sci-hub.bz (uses a separate certificate and ip address -- 18.104.22.168)
And a tor site: scihub22266oqcxt.onion
The fundamental difference of content-addressed networks is their resiliency in the face a single authority trying to track down all of the sources that have copies of the content.
Even though IPFS is still in its infancy, one of its primary goals is to solve the problem of content suddenly disappearing from the Internet.
I don't know that the sci-hub underlying database is available outside of the site. I expect with growth they will need to move to torrents or similar to minimize their bandwidth requirements.
yes, although their bandwidth is horrible
.org was their original domain which was pulled a while ago.
They are still posting updates there. Hopefully they don't get that pulled too.