Yup, and to complicate matters more those resolvers you're talking to may be talking to more caching resolvers. For a given application server it might be: -

Yup, and to complicate matters more those resolvers you're talking to may be talking to more caching resolvers. For a given application server it might be: - check local dns caching resolver - check local network caching resolver - if internal domain, check local authoritative resolver - if public domain check isp resolver - recursively resolve from there