How can I verify an applicant's claim to past military service?

So who are you, and why do you need this information? I would think that information would be confidential.

What country are you in?

Have you tried this (http://www.recordsbase.com/?act=military&fc=89&fck=service&utm_source=adw&utm_medium=cpc&utm_campaign=military&creativeid=g10176092264&utm_term=military%20service&group=adw-military-service-records&network=s&site=&ran=5732543552030094213&target=&aceid=&asl=[name]&pos=1t1&mob=&match=b&gclid=CP-Io-3qlbMCFSOnPAodgGwAKw)?