OK lets take a step back and think how a site gets indexed. Generally a site is visited by a spider coming from a third party site via an outbound link.
Therefore if the site providing the backlink is 'findable' on the search engine of choice it will be counted (in very general terms)
Don't get caught up in building multiple sets of results, think in term that for a sites backlink to give me benefit if its listed on the search engine I'm interested in and its related to my site, its a good link... (There are exceptions to this but its a good general guide)
Avoid back linking schemes and other short cuts...
Also avoid any tool that will give you a flood of links. In short if you have a site with few links, generating hundreds in a short period of time will potentially cause a Google flag etc.. Think in terms of short and steady and you wont go far wrong.