I think that DNA testing can tell if you have "Indian" in you, but it certainly can't tell what actual tribe you belong to.
I've read somewhere that to be a Cherokee, the Cherokee tribe itself has to make that determination.
Anyone can "claim" to be Cherokee, but if they say No you're not, you aren't Cherokee.
From what I've read, the Indians themselves had no real concept of ethnicity. When the tribe started running low on children due to war, disease or just diminished birth rates, they would go grab some kids from wherever they could to keep things going. Read a fascinating book on European children who were kidnapped from settlers. They always tried to get children between 5 and 12 I think...younger than 5 and they wouldn't survive, older than 12 and they wouldn't adapt.
In many instances, when the kids had the opportunity to return to their families, they preferred to stay with the Indians.
Some if not all tribes require and affiliation to be considered a member of the tribe. The person has to spend time every year or so at the reservation. The person must show descent from a registered member of the tribe. Being accepted as a member of a tribe is jealously protected.
DNA results are not accepted as proof of lineage. Also, if you take a DNA test it may not show indian ancestry when it should. It might show Asian but many indian tribes descended from Asian migration.
DNA simply isn’t the all powerful tool many think it to be. But, it can provide interesting results. I did a DNA test and discovered that my grandmother was an unmarried single mom. She later married and my ‘grandfather’ adopted my dad. Also, additional DNA testing pretty well identified my true grandfather. All are passed now so it doesn’t really matter.