Yes, you are confused. IBM certifies people by roles, and each role requries one or more test to be passed. While roles (and tests) you chose depends on several factors including:
- Platform: DB2 for Linux, UINX, Windows or DB2 for z/OS (OS/390)
- Certification Role: DBA or Application Developer
- Version: 7.1 or 8.1
- Level of expertise: Entry, Intermediate, or Advanced
See
http://www-1.ibm.com/certify/certs/rolesi.shtml