Data Guard is one of the high availability, disaster recovery and data protection architecture from Oracle. The Active Data Guard in Oracle Database 11g has brought significant changes in the existing architecture. This paper will study these changes and will see how active Data Guard is providing high availability with offloading workload to one or more standby databases and providing the opportunity to query real time data in standby databases. Finally this study will see how it provides the way to perform different write operations on primary database through standby databases.