read the transcript!
ping checks if you can reach a host and how long the host took to reply
Australia is 17,000 km from me. at the speed of light it’s still far!
ping works by sending an ICMP packet and waiting for a reply
ping: to: health.gov.au hello!
health.gov.au: I’m here!
myth: if a host doesn’t reply to ping, that means it’s down
Some hosts never respond to ICMP packets. This is why traceroute shows “…” sometimes.
host (thinking): not listening!!
traceroute tells you the path a packet takes to get to a destination
me → my ISP → NYC → Sacramento → Australia
$ traceroute health.gov.au
1: 192.168.1.1 3ms ← router
2:...yul.ebox.ca 12 ms ← ISP
8: NYC4. ALTER.NET 24 ms ← here the packet crossed the USA! from NYC- Sacramento!
9: SAC1.ALTER.NET 97 ms
16: health.gov.au 253ms ← crossing the US takes time
like traceroute, but nicer output! try it!
look up how traceroute works (using TTLs!) it’s simple + cool!