named

[Richard Pieri]

On Dec 2, 2010, at 10:42 AM, Dan Ritter wrote:
> 
> Akamai doesn't use short TTLs for load balancing. Akamai uses short
> TTLs for failover, so that your preferred node going down doesn't
> simultaneously kill Apple, CNN, the NYTimes, and all their other customers
> and end up causing you to complain to your ISP that half the Net is down.

The big problem with DNS roulette failover is if a node faults then users are stuck with a fault until the RR expires.  So short TTLs, but this means many expensive DNS lookups and relatively few cache hits, and you're still screwed if someone upstream ignores or rewrites TTLs and you get a faulted node.  There are several right ways to do this kind of failover.  Playing DNS roulette games isn't among them.  It's just a hack that foists the problems onto the users.

--Rich P.