As stated before. Run a search you will find most of your certification exam questions ahev been answered before.
Right now though I find your question to be to open and also for 2 different distro's of Unix. Do you want to know about Solaris? or HP? What type of certification you asking about?
If your looking for the Solaris certification paths then go to
http://training.sun.com/US/certification/ and then select what certification path you wish to have a look at.There are 5 different certification paths there.
Don't ask me about the HP certification paths, have a look on the web site.
By the sounds of what you are asking for everything you want to know can be found on the web site for that O/S.