Total there are 3 rounds. First is online Aptitude plus technical test of 100 marks. For aptitude test refer R. S. Agarwal and you should have knowledge of C++,OOPS Concepts,SQL,basic of Networking and Data base system.Second is Technical round, mostly they are asking questions related to your resume.As I applied for Java development they asked me questions on Core JAVA and SQL.then 3rd round is machine test they given us 1 problem statement, we have to prepare code for it.But for trainee position they don't expect complete code.