Sardinian is a Romance language that resorts to various strategies to express total and partial questions. Apart from intonation, Sardinian makes a particular use of the marker a (< lat. aut 'or') and of fronting. The syntactic properties of interrogative utterances presented show the incompatibility of fronting and marking through the interrogative marker a. The paper discusses the reasons for this incompatibility, and it describes the interferences between negation and the interrogatives. The hypothesis presented is that negation and interrogative marking are incompatible because they are associated to different focus domains that come to clash.