Using ping is a really crude way of establishing the 'darkness' of a prefix.
Complete prefixes just block off all ICMP incoming traffic, as do many core internet infra-structural devices (although they may pass them on, they won't answer pings directed to them).
Complete prefixes just block off all ICMP incoming traffic, as do many core internet infra-structural devices (although they may pass them on, they won't answer pings directed to them).