Value of a sub-domain compared to a domain

[Michael_Rock]

Hello, I have a client that has a blog with a domain of www.domain-a.com and a website www.domain-b.com. I told him that instead of trying to promote and rank with two different sites for the same thing that he should have his blog on www.domain-b.com so that any links, notices, visits, social mentions, etc. all point to one domain name and he was in agreement.

But he uses a CMS (content management system) for his website and his hosting/design companey said it would be easier to set up his blog as a sub-domain of his site. www.blog.domain-b.com.

My question is will the blog on a sub domain (www.blog.domain-b.com) help out link juice, ranking, etc. for the domain name www.domain-b.com just as must as a blog at www.domain-b.com/blog would help out the domain name www.domain-b.com?

I know that Google used to treat links form sub domains as external but recently changed the treatment of these links to internal.

P.S. The current blog at www.domain-a.com holds very little value currently.

[Michael_Rock]

Okay, I remembered an article Rand did on subdomains vs. folders and found it so this brings up more questions.

Quote from article: "Subdomains DO NOT always inherit all of the positive metrics and ranking ability of other subdomains on a given root domain."

But does the subdomain give positive metrics to the given root domain when it does well?
(This is the question that I started out with)

Quote from article: "Some subdomains GET NO BENEFIT from the root domain they're on. These include sites like Wordpress.com, Blogspot.com, Typepad.com, and many others where anyone can create their own subdomain to begin publishing."

The blog will be Wordpress, but will the blog give benefit to the root domain?
(Same question I started out with)

Was this article written before or after Google changed its mind about how to treat links from a subdomain from treating them from and external site to treating them like from an internal site? Does this article even apply anymore?

[MauroMazzocchini]

Hi Michael, I think that in your case there should be no big difference between the two implementations.

It all depends on how it's structured and linked together, because, as you said, now Google tends to treat subdomains exactly the same as internal links. (Regarding this statement I must say that I've seen websites reacting in different ways and not always following what Google is telling us)

Of course in both cases you would definitely improve the domain authority, while you would have to work on linking well the blog with the website sections in order to pass link juice to the right pages.