DAO is the only data access technology that supports 16-bit operations. If your application must run within a 16-bit environment, DAO is the only choice.
If your application must access both native Microsoft Jet and ODBC resources, DAO provides a consistent programming model (although you should consider using OLE DB data providers and the uniform data access model provided by ADO).
If your application must access remote data sources, DAO and its companion (the Microsoft Jet database engine) are a poor choice because they are slow and consume far more resources than the newer data access technologies (such as ADO or RDO).
If you're experienced in using DAO and have large amounts of existing DAO code, or just need to extend an existing application that uses a Microsoft Jet database, DAO may still work for you. The drawback is that as your application requires other types of data sources, DAO cannot provide data access. Eventually, you'll want to take advantage of the design, coding, and performance benefits provided by ADO.