[stonogo]

No "Enterprise Customer" is using github without a fallback plan. Github is in no way stable enough to rely on for business-critical work; fortunately, git is distributed and cnames exist, so it's easy to seamlessly fall back to competent hosting as needed.

[tomschlick]

Github has a standalone server you can run inside your own firewall. Thats where their big bucks come from and most likely what the commenter meant by enterprise.

https://enterprise.github.com/home