I asked this question:
In the content, there is the term "shortcatapp". But when I search using that term, results = 0. When I search "http://shortcatapp.com", then there is a result.
It looks like the search is using "exact match" rather than "contains" or "like".
It'll be very useful if SU allow partially match search. Sometime user won't remember the full phrases and it's where partially match search shine.