I'd like to have your opinion on this. If one has a domain abc.com and multiple sub domains xyz.abc.com, efg.abc.com etc. and if he builds one way back links only to the toplevel domain i.e abc.com will this help all the sub domains to rank well OR he has to treat every sub domain as an independent one and build links to all?
In my own experiences, also building backlinks for your sub domains would be really helpful for your top level domain. This is another form of deep linking, IMO. Have a nice day,
If you build link for your main domin it will help your subdomin but not much beside of building link for your main domin you also need to do build link for your sub domin too
Google ranks pages not domain. So you need to have backlinks pointing to each and every page that you wish to optimize for. Having said that, every links that you build to abc.com will indirectly contribute to your site ranking as it increases the "site link" Consider a simple example : you have a page optimized for "cheap baby crib" a) Backlinks to the page (eg xyz.abc.com) = 10 b) Sitelinks to the domain (abc.com) = 2,300 Then you have a competitor (eg yyy.com) a) Backlinks to the page (eg yyy.com/babycrib) = 10 b) Sitelinks to the domain (yyy.com) = 200 In the above example, you will have the advantage to outrank yyy.com simply because you have high number of site links.
subdomains are considered separate sites so link building for the main site will not help the subdomain much. if u want to pass link juice from the main domain, then use folders instead of subdomains. instead of sub.abc.com, use abc.com/sub. this way your sub-folders are part of the site and will get link juice form the main index page
i think it is help little bit but not effective for our site it is necessary to buil link building for every sub domain also?
I agree with digitaltours, its not effective. You must find backlinks with different domain. Free domain like blogspot.com or wordpress.com its doesn't matter. you can find backlinks via youtube, but don't create account just input your links, you must active on youtube (upload, comments, etc). the effective ways are, blogwalking on other blog that has same niche/topic with your site.
It used to be helped a long time ago and Google had changed a way they treat with subdomain because of this gaming attempt. Google have treated subdomain as separate domain for now.