I'd like to see a fully distributed version. All you need is 4B hosts (IPV6 FTW) named N.domain.com (where N varies from 0 to 4B-1). The driver app sends N to the first host (0.domain.com). Each host compares the incoming N with their N.domain.com name; if they match, return the host's true/false value. If they don't match, forward the request to (N+1).domain.com and return the result.