|
It has to do with traffic volume (steady, not high). A strong/steady rank for a popular keyword/phrase or domain name phrase. And as Jdoughs pointed out, an easy to navigate/spider website. Domain age appears to play a role, but the domain doesn't have to be super old.
I have found that a proper menu structure (site flow/spider flow), backed with steady keyword positions, plays a major role in getting site links.
|