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I'm doing a SEO site audit, and I've discovered that the site uses a Content Delivery Network (CDN) that's being crawled and indexed by Google. There are two sub-domains from the CDN that are being crawled and indexed. A small number of organic search visitors have come through these two sub domains. So the CDN based content is out-ranking the root domain, in a small number of cases.

It's a huge duplicate content issue (tens of thousands of URLs being crawled) - what's the best way to prevent the crawling and indexing of a CDN like this? Exclude via robots.txt?

Additionally, the use of relative canonical tags (instead of absolute) appear to be contributing to this problem as well. As I understand it, these canonical tags are telling the SEs that each sub domain is the "home" of the content/URL.

Thanks!

Scott

Yes, you assumptions are correct. I'm concerned with similar aliases, typo domains, etc.

So the best case scenario is doing at the hosting level. What if that is not an option, and I have to do 301 redirects from the registrar level? Next best option?

For sites with multiple top-level domains that have been secured for a business or organization, I'm curious as to what is considered best practice for setting up 301 redirects for secondary domains. Is it best to do the 301 redirects at the registrar level, or the hosting level? So that .net, .biz, or other secondary domains funnel visitors to the correct primary/main domain name.

I'm looking for the "best practice" answer and want to avoid duplicate content problems, or penalties from the search engines. I'm not trying to game the system with dozens of domain names, simply the handful of domains that are important to the client.

I've seen some registrars recommend hosting secondary domains, and doing redirects from the hosting level (and they use meta refresh for "domain forwarding," which I want to avoid). It seems rather wasteful to set up hosting for a secondary domain and then 301 each URL.