16.4 Network Commands
16.4.1 The ping utility
Ping (Packet Internet Groper) is a very useful utility that is part of the basic TCP/IP protocols package and is standard with every UNIX system. A computer that is running the TCP/IP protocol stack can make use of the ping command.

Ping is a good low-level troubleshooting tool. The ping command tests basic connectivity between TCP/IP hosts by sending an ICMP (Internet Control Message Protocol) echo request to another computer or "host" on a TCP/IP network. If there is a reply from the destination host, then there is a good connection between them. Ping uses IP datagrams to pass connection information, so a ping will test from the physical layer (layer 1) of the OSI model up through the network layer (layer 3). If you are unable to run an application on a remote host, you can ping it as a basic connectivity test. If you do not get a response, the problem may not be with the application, but instead, the host may be down or the network link may be down.

Note: In order to use the ping command in Solaris, you may need to specify the full pathname of:  /usr/sbin/ping 

Any network operating system that is running the TCP/IP protocol can send and respond to ping. You can ping the name of a host computer if you have a naming service running such as Domain Name Service (DNS) or if you have entered the host name and IP address in your /etc/inet/hosts file. If not, you can directly ping the IP address of the host, which is preferred since it is a more basic test of connectivity. Figure shows an example using the ping command.
Interactive Media Activity (Flash, 95 kB)
  Using the ping Command

In this media activity, you are logged in as user2 and your current working directory is /home/user2. Type the commands that would accomplish the following objectives. 
Note: Be sure to press enter after each one. Click on step 1 to begin.