SSL Certificate Web Server Type

SSL Certificate Web Server Type

I am attempting to setup an SSL Certificate. I have generated my data from the ADSSP certificate tool, but now my ISP that I am getting the certificate from, have asked what my "Web Server Type" is?

ADSSP is installed on a Windows 2008R2 server, so the closest to this in their options is "Microsoft IIS 5+ or later" or is it something else? I have noticed people have mentioned tomcat in some of the queries in the forum, so do I choose that?
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