What does it mean when I ping an IP from the terminal

Question

I am trying to ping an IP from our machine but I am getting 100% packet loss when I do this for particular domain - cox.net

for example -

ping -I 199.106.175.128 gmail.com
PING gmail.com (216.58.214.37) from 199.106.175.128 : 56(84) bytes of data.
64 bytes from fra15s09-in-f37.1e100.net (216.58.214.37): icmp_seq=1 ttl=44     time=150 ms
64 bytes from fra15s09-in-f37.1e100.net (216.58.214.37): icmp_seq=2 ttl=44 time=150 ms
64 bytes from fra15s09-in-f37.1e100.net (216.58.214.37): icmp_seq=3 ttl=44 time=150 ms

--- gmail.com ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2000ms

But when I do this for cox.net with same IP I am getting 100% packet loss.

PING cox.net (68.99.123.161) from 199.106.175.128 : 56(84) bytes of data.

--- cox.net ping statistics ---
5 packets transmitted, 0 received, 100% packet loss, time 3999ms

does this indicate that my IP is not reachable to cox.net server and reachable to gmail and rest all domain? Can someone please let me know what does it mean?

Answer 1

For the cox.net it means that it's server/firewall is apparently setup to ignore all ICMP echo requests (I tried to ping it and can confirm same), then your ping tool just can't get any ICMP echo replies at all (to the ICMP echo requests it sent to server) and shows 100% packet loss. However the server is alive and is able to reply other types of traffic, like HTTP on tcp port 80, as you know by accessing it on your browser.

Ping may be a good tool to check for packet loss, however remote server needs to be setup to reply ICMP echo requests, if you get no replies at all to some server then it either means that the server is not reachable/down or it is setup to ignore ICMP echo requests, you have no way to know that with ping.

There is no "universal" way to know if some server is active/reachable, as server/firewall may be setup to reply just for some specific protocols and specific ports but completely ignore anything else, then it may be different for each server...