Automatic Location Detection using GeoIP
The location detection in Ethnio is done using GeoIP powered by one of the most accurate providers in the world DB-IP. We basically look at a combination of IP address and browser strings which generally include location. This practice isn't perfect - location detection only has about 90% accuracy, but it's meant to at least offer some ability to sort or filter on the responses page.
Netflix does the same exact thing (with a slightly different engineering budget) so VPNs and other location-spoofing methods can always break GeoIP detection.
You can disable this feature under account >> profile but it's turned on by default. Assuming you have it turn on, the location will be displayed underneath each Respondent name under Responses: