How do clients handle DNS requests to failed servers?

If a server fails then DNS continues to send requests to the unavailable machine that can waste bandwidth. This problem occurs only during startup for a Java client application. WebLogic Server caches the DNS entries and removes the unavailable ones, to prevent the client from accessing a failed server again it avoids unnecessary DNS requests with browser-based clients, It uses third-party load-balancer products such as Resonate, BigIP, Alteon, and LocalDirector that products mask multiple DNS addresses as a single address. It also provides more sophisticated load-balancing options than round-robin and keeps track of failed servers to avoid routing unnecessary requests.