DAO (data access model) is the first Data Access Model that is created for local databases which contains built-in Jet engine which overcome with some problem like performance and functionality issues. After this RDO (Remote Data Object) and ADO (Active Data Object) comes in market which basically designed for Client Server applications but soon ADO is more comfort then RDO. ADO a good architecture. ADO contained all the data in a recordset object which creates problems when implemented on the network where firewalls exist. Because ADO was a connected data access, which make connection open until the application is closed. This creates issue like database security and network traffic. Because open database connections use system resources to a maximum extent making the system performance less effective. This helps in developing of ADO.NET.