Here’s what to do:
1. Register to receive a Second Shot voucher for either a single exam or a certification pack. Click a link in the table below to get started.
2 . Using the Second Shot voucher number, schedule and pay to take your initial exam through our testing provider, Prometric, at 
http://www.register.prometric.com.
3. Take your exam.
4. If you do not pass your exam the first time, you may register to take the same exam again at no charge, via 
http://www.register.prometric.com. Provide them with the same Second Shot exam voucher number when registering the second time. NOTE: Please wait one day after failing the exam to register for the retake, to allow for test results to be entered into the system.
Full details: 
Get a Second Shot at Microsoft certification for free