Monitors should trigger a DNS lookup on a server when it detects that its IP has changed

If the monitor detects that the IP address that a hostname resolves to has changed, it should trigger a DNS lookup immediately. This would help solve the problem where a container is destroyed and created with a new IP address but the same hostname and connections to the old IP address can be made but they time out. The monitor will be the first to detect this so it should trigger an immediate DNS lookup.