I want to install a CDN service on a subdomain of my site. Since the service requires the subdomain to use CNAME (to point to their servers), will that affect the SEO of the subdomain?

I know that the domain of the contents remains the same, but I am afraid that the CNAME can affect the SEO since the CDN domain does not match with my site.

1 Answer 1


Google and other search engines check the pages that the content is embedded from, they care little where that content is coming from, should it be from another site or a CDN.

There are millions of sites that use the default domains hosted by the likes of Rackspace/Amazon and so on without the use of custom domains. In fact using a custom domain with the likes of a content delivery network actually causes an additional lookup which causes a slight delay, for example if you use cdn.sitename.com instead of AS2010.RackspaceCDN.com for example your actually causing an extra lookup because cdn.sitename.com resolves to AS2010.RackspaceCDN.com so its 2 DNS lookups rather than one.

Anyway, in short. Using a CDN without a custom subdomain, domain or anyelse does not have any effect what's so ever or at least that we know off, millions don't also when CDN first came out you couldn't use custom domains ;)

  • Dont quite agree with you. SEMrush and many others claim that using CNAMEs boost your domain authority: semrush.com/blog/…
    – Paras
    Commented Jan 21, 2019 at 16:02
  • @Paras non-sense, little to no evidence to support such a theory. Just because some guest blogger posted on SemRush doesn't make it true. The vast majority of websites including some of the most popular websites in the world for that matter use 'stock' DNS provided by various cloud services just fine. Google, indexes and scores pages, it doesn't look care if they originated from your domain or another domain since that would be to say you don't benefit from Vimeo, YouTube, Pinterest and so forth everytime you embed them on the page, non-sense. Commented Jan 22, 2019 at 14:28
  • Simon, who are you exactly? Founder of Google? What evidence have you presented to support your claim? Should we agree just because "Simon says"?
    – Paras
    Commented Jan 22, 2019 at 14:31
  • Your not looking at it logically. Google and Bing know that millions of websites use content delivery networks and no case study has ever proven using your custom CDN domain over a 3rd party is more beneficial, in fact, you're causing a DNS delay that is simply not necessary because you 'think'it's better. The vast majority of top websites in the world use CDN's provided by Amazon, MaxCDN, Azure, Google Cloud, Rackspace without custom domains, these companies pump millions into SEO, I'm fairly confident, if they believed it gave them the edge, everyone would be doing it. Commented Jan 22, 2019 at 15:31
  • I don't think there's documentation to support anything. Noone really knows what's really going on with Google's algorithm. But I'd rather be better safe than sorry. Also, some interesting facts: CDNs such as Cloudflare (DA 96) and even URL shorteners like bit.ly (DA 97) have incredibly high domain authorities. Has Moz screwed up or does Google also regard them with equal importance? That's anyone's guess.
    – Paras
    Commented Jan 22, 2019 at 15:49

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.