[filiadragongurl]

If you're talking about how to ask a question in casual form (that's when you end sentences in da instead of desu) it's like this:

Formal: Nan desu ka?
Casual: Nani? (with questioning intonation)

So aside from "nandaka" meaning "somehow" or when you're confused about something you don't get "da ka" together. I believe your question was aimed at the casual style questions, so just say the sentence like usual, but end with a questioning intonation.

Make sense?