Abstract

With the increased use of DNS anycast, load balancing, and other

mechanisms allowing more than one DNS name server to share a single

IP address, it is sometimes difficult to tell which of a pool of name

servers has answered a particular query. While existing ad-hoc

mechanisms allow an operator to send follow-up queries when it is

necessary to debug such a configuration, the only completely reliable

way to obtain the identity of the name server that responded is to

have the name server include this information in the response itself.

This note defines a protocol extension to support this functionality.