The certification exams for VCAP5-DCA and VCAP5-DCD on vSphere versions 5.0/5.1 are set to expire on January 31, 2015. The exams for vSphere version 5.5 will continue to be available. So, if you plan to seek the VCAP5-DCA certification and prefer to be tested on vSphere 5.0 / 5.1, then you should plan to take the VDCA510 exam by the end of January. Likewise, if you plan to seek the VCAP5-DCD certification and prefer to be tested on vSphere 5.0 / 5.1, then you should plan to take the VCDC510 exam by the end of January. Otherwise, you can take the VDCA550 and VDCD550 exams, which cover vSphere 5.5, at any time.
For those of you that choose to use the Official VMware VCAP5-DCA Cert Guide from the VMware Press to prepare for the VCAP5-DCA exams, be sure to purchase the Premium Edition, which includes online content that covers the blueprint for the VDCA550 exam. The online materials include information on using the vSphere Web Client, new features in vSphere 5.5, items that covered in the VDCA550 blueprint (but not covered in the VDCA510 blueprint), and additional practice exams.