DNS Racing -Multi ISP load balancing with failover using DNS.

Maren S. Leizaola leizaola at sarnic.hk.com
Sun May 29 21:12:11 UTC 2011

DNS-Racing is a method of load balancing access to servers which are 
multi homed and provides lowest latency access to users and network 
resilience to ISP/routing failure.
**What does it do?*
It permits a server which is connected to two ISPs to use the optimal 
ISP when transferring data to a user regardless of TCP/UDP protocol. 
When a user does a DNS look up it will select the IP address of the 
server to which is closest. If one of the two ISPs is down or there is a 
routing problem the user will only be offered the IP address of the 
server it has access to. It also means that traffic will have the lowest 

DNS Racing can be done with 2 or more providers and permits to scale 
network bandwidth horizontally by adding more providers. In theory up to 
14 different ISPs/IPs could be used to do the delivery.

IT is a poor man’s replacement for BGP multihoming and IP anycast.

For those that want a full explanation and an implementation guide.

Hey it is Free and you can implement it using BIND.


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