I think .test is the TLD is the one most likely to work as expected as for all use cases as .localhost might be expected to only ever point to the loopback IP a

I think .test is the TLD is the one most likely to work as expected as for all use cases as .localhost might be expected to only ever point to the loopback IP address. If anyone does something more complicated (like using a vagrant private network ip address), you might find some tools break unexpectedly. Edit: the newer version of the docs have more details (in section 6) on the differences to be expected between test, localhost, example and invalid domains. see: https://tools.ietf.org/html/rfc6761 https://tools.ietf.org/html/rfc6761