The document discusses the root servers which are the first step in resolving host names on the internet. It explains that there are 13 root server addresses which are implemented using anycast so there are actually over 600 physical server locations. It provides background on how DNS works to map names to internet resources and different types of DNS records. It also gives a brief history of how DNS evolved from the early ARPANET and how root servers are run by independent organizations with locations around the world.