CompTIA Network+

Answer: B - The TCP/IP utility “ICMP Echo request,” also called Ping, can be used to locate a black hole router.

Key Takeaway: When the MTU, or maximum transmission unit, is larger than the maximum packet size of the receiving router, and the receiving router does not send a destination unreachable response, several different problems can occur depending on the application sending the request. This can cause packets to be lost, resulting in what is commonly described as a “black hole” router. As the Ping utility can be configured with alternate parameters such as a different buffer size and the “don’t fragment” syntax, this makes it the perfect utility to troubleshoot why packets are not arriving at their destination, therefore locating the black hole router.