When a phrase is used between the interrogative word and "dai", the plain form of verb or i-adjective + ndai”. is used.
When a noun or na-adjective is in the middle of the sentence, "dai or nandai" is used.
Itsu kaigi ga aru ndai.
Doko no keeki ga oishii ndai.
Nani ga warui ndai.
Dare ga byooki nandai.
Women and children mainly use "no".
Men mainly use "kai" and "dai".
People in superior positions (i.e., bosses or teachers) often use these words when speaking to inferiors.