Never heard of Sun? And don't forget about all the ColdFusion sites, a few of which are still around
SunOS - which well known dotCom era startups run their web servers on SunOS? (beside Sun) There was also SGI with Irix, etc but beside some graphical niche market, etc. How is this relevant to dotcom?
Pretty much everybody. Remember those absurd Sun Microsystems ads that claimed "We're the dot in dotcom"? They had $15bn in revenue in 2000; even mighty Microsoft only had $22bn that year.
Linux was so far behind Solaris and the other commercial UNIXes in features and security in 1998-2000 that it wasn't even a blip on the radar.