Source: http://www.seochat.com/c/a/search-engine-optimization-help/need- know-improve-seo-using-cdns/
A Content Delivery Network (CDN) can improve a site’s page load time and traffic when used correctly. Here are common CDN SEO myths.
1. Google crawlers are blocked by CDNs – bot blockers do not block crawlers from search engines. However, they block bad bots that steal content.
2. CDNs create duplicate content – Google will not see multiple copies of pages but a single copy with one URL.
3. Sites with CDN have lesser chances of ranking for their location – CDNs recognize server locations to make sure there are no localization errors. Google looks at webmaster tools settings.
4. Multiple sites on a single IP are bad for SEO – according to an official Google representative, they do not treat sites hosted on CDNs differently.