Bump... Anyone?

That is a highly debated topic and there is no real way of knowing for sure one way or the other.

A lot of people say it has to be indexed, others say it has to be cached and others say it just needs to be crawled.

Personally I just ensure links are indexed by building links to them in a multi tiered setup. The only thing you can be 100% sure about is Google definetly counts links that are indexed.

when the google robot crawls a page it checks all the links available on the page , and take them as a backlink for those websites or pages whose link is on the page google is crawling..

it is all about indexing a page , when google index a page then it checks all the links available on the page, that is why everyone wants their backlinks pages to be indexed soon and even use paid services for that.