Ping 

A ping is perhaps the most commonly used tool when troubleshooting a network. Ping (Packet Internet Groper) tool is included with most operating systems. It is invoked using a ping command. Ping command uses ICMP (Internet Control Message Protocol). Ping works by sending an ICMP echo request message to the specified IP address. If the computer with the destination IP address is reachable, it responds with an ICMP echo reply message.

 

A ping command usually outputs some other information about a network performance, e.g. a round-trip time, a time to send an ICMP request packetand receive an ICMP reply packet.

 

Here is an output of the ping command from Windows 7:

 

 

 In the example above we have pinged the ip address 10.10.100.1. By default, ping on Windows sends four ICMP request packets. As you can see from the output above, the host with the IP address of 10.10.100.1 is reachable and has replied with four ICMP reply packets. You can also see that the remote host has replied within 1 ms, which indicates that the network is not congested.