Last updated: 2017-05-10

Source: https://support.freshdesk.com/support/solutions/articles/225438-can-i-use-my-vanity-url-or-cname-to-make-an-api-call-

As of now, the V2 of Freshdesk's API supports only the Freshdesk URL on HTTPs. Making calls using the vanity URL isn't supported.