I did my CNA class online and did clinicals at a local LTC where I now work. There are legitimate organizations out there who offer the classes online and it was much cheaper for me to take it through the company I did versus doing it through the local community college, which isn't even that local to where I live. The company I did my class through even helped us get registered for our state test and was approved by our state health agency as a legitimate CNA class provider.
If you question the integrity and legitimacy of this company, check with your state health department about places which are certified and verified to provide adequate and appropriate services to get your CNA certification. I know my state maintains a database of class providers.