[KenanSulayman]

Wouldn't it be possible to use DNS for this, with multiple A entries per LB, a TTL of 30 or 60? And remove unhealthy servers from the list? That would even come with IPv6 support.

Then you could address the LB with an address like some-service.lb.intranet and just use that where ever you would use the original service.

[buzer]

Designs such as GLB can (I haven't looked deeply enough in GLB specifically to see if they can do it or not, but I would assume so) handle director level failures mid-flow, i.e. connection won't be interrupted even if one them dies (packet losses are still likely, but TCP will take care of them). That allows a lot faster recovery than solutions that depend on client's DNS settings.

Additionally DNS will leave your load balancing at the mercy of ISPs DNS server settings. At least in the past it wasn't exactly unheard of that ISPs only cached single A entry so all of their clients would be directed to single server.

That said, DNS based load balancing is generally good enough solution for most of people.

[blantonl]

Problem here is you assume that every client honors the TTL. That is a very bad assumption to make.

[user5994461]

DNS failover works well in practice.

[merb]

DNS failover looks like a neat idea, but does not work well that good. Until a new DNS entry propagates it could take a really really long time. also using anycast/ecmp via bgp means that you have a single ip that is highly redudant because it can be backed by many servers.