Anycast

• Same IP
• Multiple Instances
• Each host has a unique (primary) IP
• Clients are routed to nearest instance
  • When we look at the internet, it is made up of Autonomous Systems (ASs), they are trying to get people to the closest resources as fast as possible.
  • You can't have two devices with the same IP address in the same broadcast domain (when the devices ARP, wither can answer and is problematic)
  • You take the IP address of that anycast value and we advertise it out through a dynamic routing protocol
    • BGP
    • Pick the best and fastest path.

• Anycast is the idea of the same IP address being used in multiple boxes all around the globe

Standard DNS query

• UDP 53
• 4.2.2.2 IS THE SECONDARY IP, They are really communicating with each uniques IP.
• Listening and answering requests on this anycast IP.
• Look at Root Servers.