The attached DIA brochure gives an idea of what a polygraph entails. I do not have any experience with DIA's polygraph program. I have only been polygraphed by NSA and CIA personnel. Both were unpleasant experiences. Polygraph operators are permitted to ask personal questions and accuse their subjects of crimes without evidence. For example, my NSA polygrapher told me one of his subjects was unable to pass his polygraph, the illegal drug question, until he confessed to him his past hard-core (I can't remember which drug, it wasn't marijuana) drug habit. He had attempted to conceal his drug habit but once he confessed to his polygrapher, got this off his chest, he passed. The polygraph experience is invasive and humiliating lacking oversight.
Full-Scope Polygraphs have two parts, the CI and Lifestyle.
CI polygraph includes only questions relevant to CI but I do not have personal experience with CI only polygraphs.
Visit antipolygraph.org for more information on the polygraph. I will post my opinions on how to maintain composure and beat the NSA and CIA polygraphers at their game in a later post. The polygraph is junk science and only works if you believe it works.