Is it rude to ask a question that ends with だ?


I'm going over the entry for のだ in my grammar dictionary, and I pretty much
understand the meaning, but I'm unsure about casual question forms:

  * んだ (male) / の (female) んだい? (male) / の? (female)

Two examples:

> 「今行くの？」(f)
>
> 「今行くんだい?」(m)

The female form I am okay with. But I have never heard だい before, and I
remember being told that it's very uncommon. I think males might simply say

> 「今行くんだ？」

Am I correct? But I've read that this can sound too interrogative or
accusatory if the intonation is not right, so how would I say it properly?

Finally, I've seen のか, what is the difference? Is it feminine?




"今行くんだい?" looks highly unnatural to me regardless of gender/situation.
Sentence-end だい in questions appear _mainly by males in fiction_ and _always
with an interrogative_ , e.g., "何故だい?" or "誰だい?" (This い is a [sentence-end
particle](https://dictionary.goo.ne.jp/jn/9100/meaning/m0u/). You can say
"行くか?", "行くのか?" and "誰だ?" but usually not "行くだ?" or "誰か?" in conversation,
right?)

"今行くんだ?" is a natural and casual way of expressing surprise and saying "(Oh,)
you're going now?" It's not particularly masculine in real-world conversation.

