Quality Linking and Reach-ability
The links you build should have reach-ability because Bill Slawski uncovered and decrypted yet another Google patent on reachability scores. The patent is named Determining reachability and was granted just a few days ago.
If you want to increase your search ranking you have to get the quality link building and before doing that you have to always check the reachability of the particular website because Search rankings might be promoted (boosted) or demoted in search results for a query based upon that reachability score calculated based upon a number of different factors.
Now you have to consider 3 things while you are generating links i.e.
1. Quality Link Building.
2. Contextual links.
3. Site’s Reachability.
So clearly based on this patent document, Google cares about the quality of sites you link to. Google is able to measure those site’s reachability and your site’s reachability.
For quality linking building : Website Developer’s Resource