As of July 19, 2013, all VMware certification exams will require authorization from VMware before scheduling an exam. VMware certification exams are delivered by a third-party testing vendor, Pearson VUE. Pearson VUE will require prior authorization from VMware before exams can be scheduled. VMware will authorize candidates upon validating email address and checking that the pre-requisites for the certification have been met. Authorizations will be processed automatically for you from vmware.com/certification.
Untill July 19 2013 the entry level exams (VCP4 and VCP5) could be booked without authorization. Other exams already required authorization.
The authentication takes between 15 and 30 minutes.
more information on certification here.