For debugging purposes, we would like to configure our pool of load balanced web servers to output an HTTP header identifying the "true" server which served the request. However, we don't know what header name this should be! Is there any pre-existing header for this? Do you have a favorite?
AFAIK there isn't a formal standard for this. What I've seen is:
Update: I found this survey of HTTP headers in the wild from 2011. My suggestion