On no particular schedule that I can discern, Microsoft offers certification candidates an occasional free “Second Shot” at certain of its certification exams. Basically, this requires that you request a “Second Shot” voucher before you schedule and pay for either a single individual technical exam, or one of the currently-available MCSA, MCSE, or MCSD “certification exam packs” — see the Second Shot page for more details. Then, if you fail the exam (or any of the exams in a certification exam pack) you can use the same Second Shot exam voucher number to register with Prometric for a free exam re-take. Each time you register (initially, or for a retake), use this URL: http://www.register.prometric.com.
Obviously, you’ll want to hang onto your Second Shot voucher so you can use it should you need it. The individual exam Second Shot promotion only applies to a single exam at a time (Microsoft puts the restriction this way: “You can only register for one exam at a time, and you cannot register for a second exam until you have taken the previous one.”), so the 15-plus percent discount pricing and the blanket Second Shot coverage on certification exam packs looks pretty attractive. That attractiveness goes up when you consider that the expiration date for single-exam Second Shot is May 31, 2013, but that’s extended to December 31, 2013 for exam packs (though you must still sign up and pay for those packs on or before May 31, 2013 to take advantage of this offer).
Thanks to Emmett Dulaney, sometime contributor to CertiCities.com, for bringing this latest return of the Second Shot offer at Microsoft to my attention!