Types of Name Servers

• DNS specifies two types of name servers

• • Primary
  • • Maintains files for its zone locally
  • Secondary
  • • When it boots, it requests files for its zone from a primary server (zone transfer)
  • A name server that contains all of the information for a zone is authoritative

• Most domains have at least two name servers

• • Redundancy for reliability
  • Usually kept physically and topologically separate

• Root name servers are authoritative for all TLDs

• • They know how to get to each TLD name server
  • Currently there are 13 (as of February 2007)
  • Run by different government and commercial organizations throughout the world
  • Targets of hacking…