Best Certification for fresher RHCSA or Oracle DBA

I suggest you opt for CCNA Cisco certified network associate or RHCSA Red Hat Certified System Administrator. These two will help you in getting a job.
Red Hat provides courses to get certified on Linux platform for basic and senior level System administrator. CCNA certification of CISCO which stands for Cisco Certified Network Associate is a certificate which validates a professional's ability to understand, configure, operate and troubleshoot medium-level switched and routed networks. It will also include the verification and implementation of connections via remote sites using WAN.
If you opt for Online Red Hat Certifications you will have the responsibility of system and you will become Linux System Administrator. Similarly if you go for CCNA you will have responsibility of Network and you will become Network Administrator.
Generally, companies seek for persons who are having both the certifications RHCE & CCNA, so that they hire only one professional for both the task and this designation is known as System and Network Administrator has lots of opportunities.