Re: Haproxy failover: DNS RR vs Virtual IP (heartbeat, keepalived)

On 01/06/2011 05:48 PM, Angelo Höngens wrote:
> Round robin is not the same as random.

Sure, but my understanding was that between caches and inconsistent usage of the list returned by RR (sometimes shuffled), the behavior in practice was far from being perfect round robin.

>
> If a host name has 4 A records, then most DNS servers (if not all) will return it round-robin. So first a.a.a.1, then a.a.a.2, then a.a.a.1, then a.a.a.2, etc.. Of course there are multiple dns servers involved and thousands of clients over the world, but in the end we almost always get a perfect 25-25-25-25 balancing.

Hm, interesting, I have seen reports of different behaviors. What kind of configurations may interfere with the ideal, near uniform balancing ?

thanks,

David Received on 2011/01/06 09:59