based on a quick perusal of the man page, the -O option will show something like "no answer yet for icmp_seq=19" when a packet doesn't get a response in time fo

based on a quick perusal of the man page, the -O option will show something like "no answer yet for icmp_seq=19" when a packet doesn't get a response in time for the next one, and at least for me the default shows the icmp_seq which increases by one for each packet sent, but is only printed on each receipt (so you can spot missing ones).