Are certifications gaurenteed for army 17C MOS?

The certifications are all provided by commercial companies. You will receive IT boot camp style training but you will still have to take the test to receive the certification.

You receive the training relevant to the certifications. That is the only guarantee. As long as you continue to pass and advance. There are various certifications that you can receive along the way as long as you pass the tests. Some certifications are just related to the training block (certificate of completion). Commercial certifications (CompTIA, Cisco, etc) are all dependent on receiving a voucher (sometimes they're not available) and passing that test. CompTIA Security+ is pretty much a requirement to perform the job of a 17C so if you can't pass that test, you can't do your job. The Army has provided me vouchers for many of the certifications I hold, as a 25B and as a 17C. I once went to a 2 week CISSP course and there were no vouchers for the test available so I received the training, but not the certification because I couldn't take the test. Received a lovely certificate of completion that only goes towards maintaining my other certifications. The bottom line is you still need to pass the tests, not just attend the training.

I'm not involved in the Cyber world, but from the 17Cs that I do know, I hear that you can get your certs. Also, just a personal idea, you can receive certs through the army COOL program. Fields with certs outside the army such as Intel, Cyber, logistics, etc can receive certs. It may take more effort on your part, but take heart. More effort is what will separate you from those just going through the motions, and will enable you to advance and stand above your peers.