Domain Name System

• People tend to use DNS names, not IP addresses
  • The sockets API lets you convert between the two
  • It’s a complicated process, though
    • A given DNS name can have many IP addresses
    • Many different IP addresses can map to the same DNS name
      • An IP address will reverse map into at most one DNS name
    • A DNS lookup may require interacting with many DNS servers
• You can use the Linux program “dig” to explore DNS

• How to use getaddrinfo()

  • The getaddrinfo() is a really powerful tool for
  • hostname can be host (like apache.com) or ip address
  • hint parameter can specify what type of address you want (see attached file for reference)
  • returns a linked list of addinfo struct that contains

  

  

  You may want to use these files as reference:

  ex15 answer.zip