Is it right strategy to link subdomains from the main domain?

[James Peterson]

Presently One of My Main Domain having 6 to 7 sub domains (which are ranking very well) but my main domain is not ranking well after the penguin update. When we analyzed we found following.

I have following Questions in my mind, please clarify me to move forward.

1. Linking to sub-domains (keyword specific) from the footer links / main navigation is it right strategy?

2. If page is placed in robots.txt, but adding "nofollow" attribute to the respective link in the page, will it be right idea?

For Ex: In the site navigation one URL placed in robots.txt, throughout the website respective link will present, so we have added "nofollow" attribute as well.Is it correct idea?

3. From the sub domains, One of the page placed Keyword specific links to Main Domain with keyword specific..is it right idea?

For Ex: XX.XYZ.com website, From "About Us" page linked to Main domain with keyword specific? WIll it be treated as Negative?

[tedster]

It normally makes a lot of sense to link from the main domain to its subdomains. However, a lot here is about intention. Do the keyword subdomains exist for the visitor's benefit, or for your site's benefit on Google? Part of this answer would hang on how full or deep each subdomain is. For instance, would this subdomain be solid enough to stand on its own as a website?

Another, related question may be even more important. Do the LINKS to those subdomains exist for the visitor's benefit or for your site's benefit with Google? You say that you use footer links, and that sets off alarms for me - that the links are the kind that a visitor might not even notice.

In the site navigation one URL placed in robots.txt, throughout the website respective link will present, so we have added "nofollow" attribute as well.Is it correct idea?

It sounds odd to me to have a URL from the site navigation to be disallowed in robots.txt. Normally, main navigation point to the top level pages for the site, those that are important to notice. Sometimes a main navigation link points to a page that requires a log-in, but googlebot won't be able to log in anyway.

So why do you not want to see a page crawled that's in the main navigation?

[bwnbwn]

For Ex: XX.XYZ.com website, From "About Us" page linked to Main domain with keyword specific? WIll it be treated as Negative?

yes is my answer it would be considered desired anchor text=desired key term=desired key search=problem.