Domain Authority and Page Rank concerns when using CNAME

[WilliamBay]

In the event that a person uses a service like Blogger or a photo service like Photo Shelter, but use a CNAME to resolve example.blogspot.com or example.photoshelter.com to example.com, how does that affect Domain Authority and Page Rank in real world results, and how does it affect the user when/if they leave the service and establish their own site?

For example:

A client has a blog on Blogger called johndoephotography.blogspot.com but uses CNAME so what is shown is johndoephotography.com.

The Domain Authority is quite high since he is really on Yahoo's domain. How does that affect SERP rankings? Is it ignored, since it is merely a sub-domain, or does the parent domain actually give a benefit?

The second part:

If John Doe decides to host his own WordPress blog, what happens to that domain authority? Has he lost it all?

[DanDeceuster]

It is important to recognize that johndoephotography.blogspot.com is NOT the same as blogspot.com. Subdomains are treated by search engines as their own domain. The SEOMoz tool does not make this distinction, and it will show domain authority for blogspot and wordpress subdomains to have the authority of blogspot.com and wordpress.com. Google does not treat them this way, or else we would see a whole lot more blogspot results in search.

I don't understand the last question. If someone has a wordpress.com blog and decides to host in on their own domain and uses wordpress.org software, do they lost the authority built to the .com? If that is what you are asking, yes. You cannot 301 redirect a blogspot or wordpress subdomain. My best solution has been to put one and only one link on the subdomain, have it go to your new domain, and hope it passes as much of its authority as possible.

[WilliamBay]

Thank you Daniel. I know it's been awhile, but now just getting back to this.

You pretty much substantiated what I thought to be true for the first part.

I have heard of some workaround 301s when going from something like Blogger to a self hosted version. And I do believe that WordPress.com has a paid option to redirect all traffic if you go to a self-hosted blog.

Thanks again!