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I am using Linkproof device for incoming load balancing based on which is based on dns. For example my linkprrof have 3 isp link.... it also act as a dns sevrer for my when someone connect me by using my dns name my linkprrof give them ip from 3 isp which ever is responding fast.

so is there any same kind of open source solution for dns based incoming load balance is possible ???


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Bind can do simple round-robin load balancing on it's own, but will not check the response time of the server. To do that you will have to choose some kind of performance measurement (for example latency) and then either rewrite the zone file or use the rrset-order command to tell it which order to deliver the records in.

Either way DNS loadbalancing is far from a perfect solution, especially for high TTL's. What will typically happen is that the DNS server of a large ISP caches your reply, and then the majority of the clients from that ISP hits the first IP in that reply. To avoid this you can set TTL 0 to disable caching, but then your DNS server will get hammered...

For more information about DNS load balancing with bind have a look at (it's not fully up to date, being written for 9.3.0, bind is at 9.7.0 now, but should give you an idea of how you can do it using bind)

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I used LinkProof in the past, now I use multiple dns with ttl=0 (Mydns with replication) and a script for check every network link. When the primary link is down, the script update dns records (inbound traffic) and change firewall rules (outbound traffic).

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hi, you mean multiple dns entry for same host? or multiple dns server? well sound like more interesting and more info if you can – sahil Apr 9 '10 at 10:08
Multiple dns server. The script uses traceroute (-i interface) to check every network link. For traceroute I use the IP address of "always on" sites (ie: google). – lg. Apr 9 '10 at 10:28

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