You can now use the On-Demand Sandbox aliases API to create a unique, global host name alias. Previously, to access a sandbox globally, you had to use an already existing DNS CNAME record that points to the sandbox origin. To access a sandbox locally, you can still create a reusable host name using a non-unique alias and generate a registration link to access the sandbox.
How: To learn how, see Use a Unique Host Name Alias.