Ping is a computer network administration utility used to test whether a particular host is reachable across an Internet Protocol (IP) network and to measure the round-trip time for packets sent from the local host to a destination computer, including the local host's own interfaces.
Ping operates by sending Internet Control Message Protocol (ICMP) echo request packets to the target host and waits for an ICMP response, sometimes casually called a pong. In the process it measures the round-trip time and records any packet loss. The results of the test are printed in form of a statistical summary of the response packets received, including the minimum, maximum, and the mean round-trip times, and sometimes the standard deviation of the mean.
The use of the ping utility is usually described as pinging a host computer. Ping has various command line options depending on the host operating system that enable special operational modes, such as to specify the packet size used as the probe, automatic repeated operation for sending a specified count of probes, time stamping options, or to perform a ping flood. Flood pinging may be abused as a simple form of denial-of-service attack, in which the attacker overwhelms the victim with ICMP echo request packets.
The following are the ping options and how to use it:
How to use it?
1. Click Start.
2. Click Run.
3. Type in "cmd" without quotes.
4. now you use ping commond. For example, c:>ping 192.168.0.1. You can also use it with its switch. For exmaple, c:>ping 192.168.0.1 -t
The option of Ping command:
-t Ping the specifed host until interrupted.
-a Resolve addresses to hostnames.
-n count Number of echo requests to send.
-l size Send buffer size.
-f Set Don't Fragment flag in packet.
-i TTL Time To Live.
-v TOS Type Of Service.
-r count Record route for count hops.
-s count Timestamp for count hops.
-j host-list Loose source route along host-list.
-k host-list Strict source route along host-list.
-w timeout Timeout in milliseconds to wait for each reply.
The following are the main error messages and what they mean.
1. TTL Expired in Transit: The TTL value determines the maximum amount of time an IP packet may live in the network without reaching its destination. It is effectively a bound on the number of routers an IP packet may pass through before being discarded. This message indicates that the TTL expired in transit. Number of required hops exceeds TTL. Increase TTL by using the ping -i switch.
2. Destination Host Unreachable: The host that you are trying to ping is down or is not operating on the network. A local or remote route does not exist for destination host. Modify the local route table or notify the router administrator.
3. Request Timed Out: The ping command timed out because there was no reply from the host. No Echo Reply messages were received due to network traffic, failure of the ARP request packet filtering, or router error. Increase the wait time using the ping -w switch.
4. Unknown Host: The IP Address or the Host Name does not exist in the network or the destination host name cannot be resolved. Verify name and availability of DNS servers.
