Hello EveryOne

I am programmer in Oracle 7.3, Now I have changed job to a company where I am programmer as well as Jr. DBA on Oracle 8.1.6 on win nt and 8.1.5 on Linux

I would like to know certain things about DBA Certification. What papers are there in certification exam and from what point I should start for it ?

Which papers I should prepare first ?
Does my working on different version will be problem ?
I would also like to know the structure of exam ? Whether subjective or objective and what online things do we have to work out ?

How much period I'll require to prepare on an avereage to prepare for these exam ?

If you can tell me the tips to work on this exam also the books and give me some tips about how to practise on machine the things and what things then I'll be very grateful to you all.

Thanks in Advance