Riigghhhttttt..... But if the server goes down and the IP is unreachable, DNS will never know and all his structure goes for naught... -----Original Message----- From: Richard A. Steenbergen [mailto:ras@e-gerbil.net] Sent: Wednesday, July 05, 2000 10:24 AM To: Jeremiah Kristal Cc: nanog@merit.edu Subject: Re: bad idea? On Wed, 5 Jul 2000, Jeremiah Kristal wrote:

Given a small, globally routable netblock to be used for front-end web servers, and a strong aversion for using DNS for any type of load balancing, would it be reasonable to build two identical servers farms with the same public IP addresses and rely on the BGP sessions with the hosing providers to remove one advertisement in the event of a problem? I've been looking at ways to ensure that the webservers are always available, short of building a network connecting hosting facilities.

In the event of a route flap, or other instability, you could potentially have traffic shifted to another server without the established TCP state, which would prompt that server to generate an RST and end the connection. If the route then comes back, you end up resetting your connection for nothing. Actually, DNS works very well for this kind of thing. Since its a stateless protocol it isn't affected by this, and once your client has its answer it continues to use the same IP, which is routed normally. I believe this is how's Akamai load balancer works (try looking up www.yahoo.com from a name server on the left coast and on the right coast). I see absolutily nothing wrong with using DNS in this manner. -- Richard A Steenbergen <ras@e-gerbil.net> http://www.e-gerbil.net/humble PGP Key ID: 0x138EA177 (67 29 D7 BC E8 18 3E DA B2 46 B3 D8 14 36 FE B6)