How would you support multiple versions of an API and why?

- Multiple version instances behind a load balancer.
- Versioned controllers behind a proxy.

Curious to hear yours thoughts and reasoning.

/api/v2/endpoint
Controllers in api/v2 only handle that version of the api. Multiple servers running the same code, all behind load balancer(s). Thus the actual server they hit is irrelevant; only the request matters.

Why support multiple versions? Easy: To support clients that haven't updated their software yet.

@Root Cool, i leaning toward something like that except putting the version in the accept header.