sending five probes (1-second interval by default, configurable via -i option) to the target host www.example.com: $ ping -c 5 www.example.com PING www.example.com (93.184.216.34): 56 data bytes 64 bytes from 93.184.216.34: icmp_seq=0 ttl=56 time=11.632 ms 64 bytes from 93.184.216.34: icmp_seq=1 ttl=56 time=11.726 ms 64 bytes from 93.184.216.34: icmp_seq=2 ttl=56 time=10.683 ms 64 bytes from 93.184.216.34: icmp_seq=3 ttl=56 time=9.674 ms 64 bytes from 93.184.216.34: icmp_seq=4 ttl=56 time=11.127 ms --- www.example.com ping statistics --- 5 packets transmitted, 5 packets received, 0.0% packet loss round-trip min/avg/max/stddev = 9.674/10.968/11.726/0.748 ms The output lists each probe message and the results obtained. Finally, it lists the statistics of the entire test. In this example, the shortest round trip time was 9.674 ms, the average was 10.968 ms, and the maximum value was 11.726 ms. The measurement had a standard deviation of 0.748 ms. Error indications In cases of no response from the target host, most implementations display either nothing or periodically print notifications about timing out. Possible ping results indicating a problem include the following: or host, network or protocol unreachable source route failed fragmentation needed or destination network/host unknown source host is isolated communication with destination network administratively prohibited communication with destination host administratively prohibited for this ToS the destination network is unreachable for this ToS the destination host is unreachable communication administratively prohibited host precedence violation precedence cutoff in effect In case of error, the target host or an intermediate router sends back an ICMP error message, for example host unreachable or TTL exceeded in transit. In addition, these messages include the first eight bytes of the original message (in this case header of the ICMP echo request, including the quench value), so the ping utility can match responses to originating queries. Message format ICMP packet Generic composition of an ICMP packet: IPv4 Header (in blue): protocol set to 1 (ICMP) and Type of Service set to 0. IPv6 Header (in blue): Next Header set to 58 (ICMP6) ICMP Header (in red): Type of ICMP message (8 bits) Code (8 bits) Checksum (16 bits), the 16-bit one's complement of the one's complement sum of the packet. For IPv4, this is calculated from the ICMP message starting with the Type field (the IP header is not included). For IPv6 this is calculated from the ICMP message, prepended with an IPv6 pseudo-header. Header Data (32 bits) field, which in this case (ICMP echo request and replies),