Ping

From TheBestLinks.com

For other uses, see Ping (disambiguation).

ping in a Windows 2000 command window

ping is the name of a computer network tool used on TCP/IP networks (such as the Internet). It provides a basic test of whether a particular host is operating properly and is reachable on the network from the testing host. It works by sending ICMP packets to the target host and listening for replies; its operation is analogous to sonar in submarines, in which an operator, trying to find a target, issues a pulse of energy (a network packet) at the target, which then bounces from the target and which is then is received by the operator, hence the name.

The tool was written by Mike Muuss.

The usefulness of ping in assisting the diagnosis of internet connectivity issues was impaired from late in 2003, when a number of Internet Service Providers filtered out ICMP Type 8 (echo request) messages at their network boundaries. Internet worms such as Welchia flooded the internet with ping requests as they sought to locate new hosts to infect, causing problems to routers across the internet.

Related network tools include traceroute and on contemporary Windows operating systems, pathping.

It has occasionally (and falsely) been stated that the name is an acronym for "Packet InterNet Grouper".

Sample ping output

The output of ping, and its cousins, generally consists of the packet size used, the host queried, the ICMP sequence number, the time to live, and the latency, with all times given in milliseconds, and times below 10 milliseconds often having low accuracy.

Below is a sample output where we ping the wikipedia.com server:

 $ ping -c 5 wikipedia.com
 PING wikipedia.com (130.94.122.195): 56 data bytes
 64 bytes from 130.94.122.195: icmp_seq=0 ttl=235 time=284.3 ms
 64 bytes from 130.94.122.195: icmp_seq=1 ttl=235 time=292.9 ms
 64 bytes from 130.94.122.195: icmp_seq=2 ttl=235 time=289.7 ms
 64 bytes from 130.94.122.195: icmp_seq=3 ttl=235 time=282.4 ms
 64 bytes from 130.94.122.195: icmp_seq=4 ttl=235 time=272.0 ms
 
 --- wikipedia.com ping statistics ---
 5 packets transmitted, 5 packets received, 0% packet loss
 round-trip min/avg/max = 272.0/284.2/292.9 ms

Slang usage

Gamers often use the term "ping" to refer to latency; a user reporting that he has a "50ms ping" is seeing this number in the server browser of the game he is playing. This means there is 50 milliseconds of delay between sending a test packet to the game server (or another player, if a server is not required) and receiving a reply. The method used by the game programmers to determine the latency is often not using the traditional ICMP echo request and reply packets but rather piggybacks the functionality onto other (usually UDP) game packets. The usage of this term is common with players of the games Starcraft, Quake, and Counterstrike.

External links

The Story of the PING Program (http://ftp.arl.mil/~mike/ping.html) by its author, Mike Muuss
Demon internet (http://www.demon.net/helpdesk/announce/2003/da2003-08-19a.shtml) explain the introduction of ICMP Type 8 filtering - 19 August 2003
Ping Utility (http://www.webmaster-toolkit.com/ping.shtml)

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