I host a small website with a well known VPS service. They provided me with one IPv4 address upon registering and said additional addresses would require justification. I requested one additional IPv4 address so as to have one for a production environment and one for a testing/QA environment. They said this was unnecessary as I could just use alternative TCP ports for the test environment.
I can live with using a non-standard port for non-production hosting, but it got me thinking, what would be valid justification? (I asked them and they didn't want to answer). Is there an industry standard for what counts as "valid" justification for additional IPv4 addresses?