A method and system detect a failed communication transmission that fails to reach a recipient after attempting to be transmitted from a sender to the recipient over a communication path. Upon detection of the failed communication, the method initiates a first inquiry process from the sender. This first inquiry process tests how far a first test communication transmission can travel from the sender to the recipient along the communication path. Similarly, upon detection of the failed communication, the method initiates a second inquiry process from the recipient. The second inquiry process tests how far a second test communication transmission can travel from the recipient to the sender along the communication path. The method combines the results of the first inquiry process and the results of the second inquiry process to determine which of the nodes in the communication path are not successfully forwarding test communications to identify at least one possibly faulty node. The identification of the possibly faulty node is then output to the sender and the recipient.