"Where does he come from?"
Translation:Dari mana dia berasal?
If you put 'dia' after 'berasal' it sounds strange - as if 'dia' somehow owns 'berasal'. Usually you put dia, kamu, saya etc after a word (object) to show that you/he/they own it. So in this case you have to specify the agent earlier in the sentence, then say what they are doing.
Imagine saying in English, instead of 'Andi is walking' you said 'Is walking Andi.' you understand what I'm trying to say, but it sounds weird.
It's the difference between saying 'From where does she come' (Dari mana dia berasal), and 'Where is her origin' (Di mana dia berasal).
You will be understood, but the first example is more active - she is coming from somewhere. The second example is more passive and focuses more on the origin than it does on the person. So the first example is better. Indonesian people would never say 'di mana' in this case, because 'dari mana' (from where) makes more sense.