This optional parameter specifies for how long time a failed remote server is removed from the forwarding list and marked as failed. The number of retries is defined by MaxFailedRequests. If no reply is received when all retries are used, the host is marked as failed and no requests are sent to it. After FailureBackoffTime time has expired, the Host is again eligible for forwarding. The unit is seconds, and the default value is 0, which means that the host is always regarded as working.