If servers are "cattle", not "pets", how can I address them?

With the move to the cloud, and the ethos of treating of servers as "cattle", rather than as "pets", how can I address them?

Currently I might have a web service on my production server, PRODUCTION01, so I can access a web service at ... http://PRODUCTION01/mywebservice.svc

But if the servers are cattle and just generated as needed, how can I address the web service?

And going even further ...

What about when we treat the servers as "chickens", i.e. we might have labels on the cattle's ears, but chickens are just a flock ...