Does using a sub-domain lessen the effectiveness of your main domain?

[d25kart]

For example a website without a blog and is a simple html site with no blogging capabilities. We go out to Blogger or Wordpress and set up the blog portion of the website using something like blog.yourdomain.com. Does this make a difference SEO wise? Is is more effective to be sure that you are using the main domain and not a sub-domain? I have heard both sides before but can't seem to find the concrete answer. Thanks for any advise out there.

[Devanur-Rafi]

Hi there,

Nothing makes a difference from an SEO standpoint unless you have good content in it. So, if you host a blog on your domain with good and relevant content that complements or goes hand-in-hand with your domain's theme or line of business, it would definitely add up to the strength of your domain overall going forward. Though its a sub-domain, treat it such that it is an entirely different domain, optimize it the way you would do any other domain. Personally, I would host the blog on my domain itself so that I don't run in to the weird world of cross linking problems especially when its hosted on the same IP address that my domain is hosted on. So if its a business need to have your blog separately, its better to go with a dedicated IP and also make sure it belongs to a different class C IP. We faced issues related to cross linking no matter how clean we tried to maintain them both. Please note that this is purely out of my experience.

Best regards,

Devanur Rafi.

[AlanBleiweiss]

Actually it's a bit more complex than Rafi explains.

If the main site is an ecommerce site (sells products), it's okay to have the blog on the main site unless you end up with a high volume of content on the blog that can weaken the "purchase" intent of the main site.  In that case, the blog on a sub-domain is actually somewhat better because it separates the "informational" intent out and can in turn build up a stronger authority signal as "informational" as a sub-domain.  But only if you drive a lot of traffic, engagement and links to the sub-domain.

If the topic is isolated to a niche topic not generally strong on the main site, that's another valuable reason for the sub-domain path. Again, by isolating it within a sub-domain you're preventing dilution of the topical focus of the main site.  That also applies if you have products or services that you can build up enough content within that niche to justify an entire sub-domain.

If the main site is informational and the blog is informational, and there is a lot of cross-topical relationshps, it's best to keep the blog as a folder/directory within the main site - in this scenario you get more value by going this route because of the commonality of intent and topical focus.