The host at this IP address is obviously operated by cybercriminals. It is running a malware botnet controller which is being used to control infected computers (bots) around the globe using a trojan horse.
Malware botnet controller located at 185.251.91.108 on port 443:
$ telnet 185.251.91.108 443
Trying 185.251.91.108…
Connected to 185.251.91.108.
Escape character is ‘^]’
Malicious domains observed on this IP address:
avyanok.com. 600 IN A 185.251.91.108
biopiof.at. 600 IN A 185.251.91.108
cajlat.fun. 600 IN A 185.251.91.108
clickclckjack.at. 600 IN A 185.251.91.108
dangerboy.at. 600 IN A 185.251.91.108
ikaryto.com. 600 IN A 185.251.91.108
immontyr.com. 600 IN A 185.251.91.108
intoolkom.at. 600 IN A 185.251.91.108
intooltak.com. 600 IN A 185.251.91.108
intromons.com. 600 IN A 185.251.91.108
irolano.com. 600 IN A 185.251.91.108
microsoftsofymicrosoftsoft.at. 600 IN A 185.251.91.108
querosityproject.com. 600 IN A 185.251.91.108
redhatbabby.at. 600 IN A 185.251.91.108
testaaaaaaaabox.xyz. 600 IN A 185.251.91.108