Oracle certifications are among the most popular in the database management area. Some of the leading certifications offered by Cisco are:

Oracle Certified Associate: Oracle OCA DBA 10g is an entry-level certification designed to test foundation skills required for database administration and maintenance. Its objectives are intended to measure a candidate's ability work as a junior team member with database administrators. The OCA DBA 10g certification is a requirement for pusuing OCP 10g certification.
Download practice tests for OCA DBA 10g Certification:

Oracle Certified Professional:
To obtain Oracle OCP DBA 10g certification, one need to pass the following exams:
1Z0-042 Oracle Database 10g: Admin - I Information
1Z0-043 Oracle Database 10g: Admin - II Information