So? This does not help me at all. If my host is down, then my site is down. If my JavaScript CDN is down and I have no fallback, my site is down as well. You imply that "totalDownTime = CDNDownTime", while really it is "totalDownTime = WebhostDownTime + CDNDownTime". Thus using a CDN, while it might make the site faster 99,999% of the time, always increases the total downtime.