Load-balancer options [closed]

i would not go for dns-based lb - exactly for the reason you list.

nginx or varnish can be your other lb/fail-over option that sits in front of appservs and acts as reverse proxy. they do require more care than hardware box but will save you quite a lot of money. be sure to put those balancers in some cluster as well [ active-passive with heartbeat will do the trick ].

If you're looking at load balancer appliances, you really can't go wrong with F5 Big-IP

edit: The reason I say just go with Big-IP is because its a nice appliance for server administrators that don't have a lot of experience with network appliances. It has a nice web interface with nearly limitless options for configuration and reporting. They are the most reliable and least expensive of all the "enterprise" load balancing options.

Here is a link to a study on application delivery options in 2007: Gartner Results