In this paper, we study about the different types of fault tolerance techniques which are used in various distributed database systems. The main focus of this research is about how the data are storedin the servers, fault detection techniques and the recovery techniques used. A fault can occur for many reasons. For example, system failure, resource failure, network between the server’s failure and any other reasons. These faults must be emphasis in order to make sure the system can work smoothly without any problem. A proper failure detector and a reliable fault tolerance technique can avoid loss and at once save the system from fail.