PageRank & SEO results of using a different domain for each company product

Question

Using Apple as an example:

 www.apple.com < --- Main company site

 www.iphone.com <--- Product

 www.imac.com <-- Product 

If each company product had its own domain name and a unique webpage or website containing an anchor link back to the main company site, would that increase the PageRank for the main company site?

If the main company site had a navigation bar with links to the different product domain sites, would that positively or negatively effect PageRank for either the company site or the product sites? (I believe this is referred to as cross-linking).

Lastly, would a 301 redirect from the product domain to a directory on the main company site (e.g., www.iphone.com -> www.apple.com/iphone) negate the benefit of the backlink?

Answer 1

PageRank will increase with each "authoritative" link to your site containing relevant content and link text related to the linked to site's content. So if the product sites are related in content but not duplicating, the PageRank for the company site should increase.

A navigational bar with links back to the product sites would be considered a "link ring". It's my understanding that if all the sites link back to each other but no other sites, a search engine may negatively rate this. I would suggest researching this more however as linking is integral to PageRank, though weighted less as of late.

A 301 back to the same site would likely be considered a "doorway page" or similar since the search engine will crawl the redirect and find the same content as the link.

Answer 2

PageRank is purely URL/page-based, so whether you have http://example.com/page, http://page.example.com or http://example-page.com/ would not change anything in how PageRank is calculated.

Using a 301-redirect to forward users (and search-engine signals like PageRank) to a different URL is generally fine, but PageRank is slightly dissipated during a redirect like that. That's not something I'd worry about though - many sites use shorter URLs or domain names for marketing purposes, but keep the actual content on their main site, and the real value comes from people just going there to actually engage with the product (or even buy it).

Answer 3

Any website that links to another site will help increase its PageRank; in a nutshell that is how PageRank is calculated.

So yes, if apple had different product domains pointing to their main site they would be included in the page ranking factor for that domain.

If the main company site has links pointing to its other product websites, that will help in the page ranking factors of those other websites, it will not harm the PageRank of the main site - you cannot lose PageRank by linking out.

However if you have many sites, say 50+, it might not be a good idea to link them all together, as Matt Cutts recently explained here: https://www.youtube.com/watch?feature=player_embedded&v=x0-jw_PfwtY.

Yes, if you 301 redirected a website that will negate the benefit of the backlink, as there is no longer any back link, the site is redirected.

Here is some further reading for more in-depth info on PageRank: http://searchengineland.com/what-is-google-pagerank-a-guide-for-searchers-webmasters-11068.