Does a subdomain hurt/help a domain?

[mlothamer]

My organization's website currently hosts research databases on a subdomain. We're relatively new to MOZ and when I ran a crawl of my site, it came back with 30K issues.... 98% of which are on this subdomain. I wish I could just remove it and call it a day, however, real and active researchers use it regularly.

My question is: Does a subdomain hurt/help a domain?

I'm seeing mixed results via Google search and browsing this forum. I'm concerned that I will not be able to fix these 30K issues as I do have access to maintain this database... and just by looking at it you can tell it was built in 2005 and hasn't been updated from an SEO perspective since. Any suggestions?

[jacobmartinnn]

As long as the subdomain is on a good host, has good UX/content and links well w/the parent. It also requires more maintenance than the parent. But if you can maintain everything then it's ok.

[R0bin_L0rd]

Hi there, in a similar vein to Kevin's comment - Google has said that subdomain/subdirectory isn't really a distinction they draw and that it's more to do with how much linking there is between the different parts whether they consider it to be the same website. That said, we don't have a good idea of what the threshold is or what historic data Google is using to make that call.

I would say this comes down to how people are using this subdomain. Do you get researchers landing on it from Google? Or is it something that they only use once they are already on your site? If you find enough researchers are coming to this subdomain from organic search then it's probably worth fixing it up because, entirely aside from the question of whether this subdomain is dragging your site down this could be a way to really strengthen your site and take advantage of a very popular resource to boost Google's respect for your site and help you rank for other things (not to mention giving your users what they want). If, on the other hand, you don't get users landing on this subdomain from organic search (you can check by going into Google Analytics for the subdomain and checking the source and medium of sessions landing on those pages) then it could be worth noindexing the subdomain. If, as you say, it's riddled with errors, you don't want Google to see it/waste time on it and users don't get there from search then by noindexing it you're saying "we don't want you to pay attention to this".

We can't know for sure how Google will treat the main domain based on this subdomain but we can plan a strategy based on use, which is often what Google tries to push webmasters towards.

[KevinBudzynski]

Google says that they really don't care if the content is on a subdomain or subfolder & this is debated. I find that they both can rank well, but subdomains require more effort to maintain. As long as the subdomain is on a good host, has good ux/content and links well w/the parent, I wouldn't worry that much and I would leave as is. Good luck.