Tools such as https://www.whatsmydns.net/ can be great for spot checking your DNS geolocation accuracy, however you may occasionally run into results that do not route as expected. This generally happens when the website's test endpoint is using a resolver that is located in another region than the test point itself. The geolocation filters will then route the request based on the location of the resolver that queried the authoritative DNS. This issue commonly arises with Chinese test points, as well as a handful of others.
The exception to resolver-based geolocation, is when edns-client-subnet resolution is enabled, and supported by the resolver as well. This allows for a more accurate resolution of the requesters geolocation, at the expense of additional queries. Read more about enabling edns-client-subnet resolution.