Best-practice for migration without down time

[Ho Kascha]

Hi there,

I wonder what's the best practice to migrate v2 to v3 without disrupting service. As I understand the docs, we should have v2 and v3 up and running, so v3 needs a new domain it's accessible under. So in the end, we migrate vom old.example.com to v3.example.com. Given everything works well, we can now shut down old.example.com. 

How can I change the hostname of v3.example.com  back to old.example.com?

Cheers,

Kevin