DNS ? Make die primary website “www.mywebsite.bulk” and once you enter deeper down direct the people to
one of the webserver by directing them to e.g. “www3.mywebsite.bulk” ?
No special treatment needed and the cgi-bin script
which directs the people may check if machines are still available – www.mywebsite.bulk might be a DNS Round-Robin which brings you some HA capabilities.
Then set the DNS TTL of the “www” host down to 5 Minutes and automatically create the DNS Zone from the hosts which are reachable.
BTW: How can a “Hardware Load-Balancer” provide better availability ? The availability of the site is the sum of the availabilitys of the essential componets. Adding more components cant provide better availability.