See
Sun's Purchase an Exam Explanation, it says:
1. Purchase exam or programming assignment.
Follow links to certification descriptions and follow easy steps to purchase online.
Exams purchased on this Web site may only be used in the U.S. If you reside outside the U.S., please select a country to inquire about products delivered in your country. Once exam vouchers are purchased you have up to one year from the date of purchase to use it. Each voucher is valid for one exam and may only be used at an Authorized Prometric
Testing Center in the country for which it was purchased. Please be aware that exam vouchers are nonrefundable for any reason.
For the Sun Certified Developer (
SCJD) Assignment (CX-310-252A) and the Sun Certified Enterprise Architect (
SCEA) Assignment (CX-310-300A), there is no time limit for completion or upload of the assignment to the CertManager database.
2. Schedule your exam.
After you have purchased your exam, contact your Authorized Prometric Testing Center to schedule your exam date, time, and location. All exams take place at Authorized Prometric Testing Centers.