PING-packet internet groper.
this command is used to check the connectivity of a single 
system with other systems(i.e. working properly).
PING is the ip address of the DNS server or remote host.

ping command is used to check the connectivity between 
computers in a network, it works with the help of ICMP-
(inernet control messaging protocol) and it is echo 
oriented protocol. if we want to block the systems not to 
ping then block the ICMP in firewall.

Ping provides to check the Physical/IP Connectivity between 
two or more devices in the network. Ping sends an ICMP 
request from source computer to destination computer and 
destination computer sends an ICMP reply

Ping [packet internet groper]is a computer network tool used to test whether a particular host is reachable across an IP network; it is also used to self test the network interface card of the computer, or as a speed test. It works by sending ICMP “echo request” packets to the target host and listening for ICMP “echo response” replies. Ping estimates the round-trip time, generally in milliseconds, records any packet loss, and prints a statistical summary when finished.