No. DANTES testing is open to all comers. The only catch is finding a test administration site if you can't get on base. For example, I am absolutely civilian, and have no ties to any military branch; I therefore am not allowed access to my local air force base. Luckily for me, a local technical college administers them. This is not a problem in most metro areas. Check out their official website DSST - GetCollegeCredit.com and check out all of the threads on here for particulars. Additionally, feel free to ask if you can't find something.
I'm Active Duty Air Force. My current base stopped giving DANTES, CLEPS, etc. over a year ago and sends us to the local community college instead. Prior to that, it had gone several years of only being able to give paper copies of the test and we were sent to the same CC for computer based testing. I don't see the inability to get on a base as a hinderance to testing.
The DSST website includes a search area where you can enter the area where you live and test centers will be displayed.
Your mileage may vary. Testing locations have been a minor inconvenience for me. The only facility I have close by only utilizes the paper-based exam. Not a huge deal, just a consideration.
I find them more convenient than CLEP (although I haven't gone in for one yet....soon!), there is a test center right next door to me in Hong Kong.