ping command

[lizadonald]

Can anybody explain what is ping command in command prompt?

[tbaher]

It is a way to measure latency (lag) between you and whatever you choose to ping.
Let's say you ping www.yahoo.com by typing

ping www.yahoo.com

it will say something like

Reply from 216.109.118.77: bytes=32 time=72ms TTL=52

This means the amount of time a piece of data (32k by default) is sent from you to it and back is 72 milliseconds.
it is useful in 2 ways .. to see if you can reach a certain host (otherwise it would say "request timed out" if u couldnt) and how far away that host is.. latency-wise. Like when playing a game on a server for instance, you know how much you will be delayed therefore how playable the game is

[lizadonald]

Thanks tbaher, in the further code, i can understand terms like Reply from...,bytes, time. But what is the meaning of TTL=52. Will u please tell me?

Reply from 216.109.118.77: bytes=32 time=72ms TTL=52

[tbaher]

Short for Time to Live, a field in the Internet Protocol (IP) that specifies how many more hops a packet can travel before being discarded or returned. (www.webopedia.com)

[lizadonald]

tbaher, nice site, it seeems very informative, i added it to my faovorite.

At present if i ping any site the message is

reply from 203..........estination net unreachable.

Inspite of this i can surf on net, how it is work?

[tbaher]

there are many reasons why you cant get a ping reply on stuff
if it says unreachable, then you are probably behind a firewall/proxy.
What this means is that your browser tells another computer to get so and so for it which then gets sent to u. (hence the word proxy .. middleman)
this is how u can browse but not get a "path" to the other host, i.e. it is not reachable
if the request simply times out then it means that the server is "reachable" but doesnt "pong" when you "ping" in a set amount of time. This amount of time is called timeout.
There are many reasons:
-It takes too long to reply so it times out. (it will usually reply to 1 or more of the 4 requests though)
-It doesnt have a ping server or is blocking the port. That basically means that it "refuses" to reply to the ping and just ignores it (or just isnt listening for pings)
-Something else is wrong. Like maybe the whole computer isnt up and running properly.

In your particular case, that whole unreachable thing means that you are not on the same network, you are not using NAT, you are probably using a firewall/proxy even if you are unaware of it (there are invisible firewalls/proxies by your ISP maybe) and that there is no DIRECT PATH to "www.yahoo.com" and thus to the internet.
Nothing to worry about unless some program doesnt work (like some online game)

[lizadonald]

tbaher, i read your answer again and again, i understood all except one line i.e. "you are not using NAT". What do u mean by "NAT"

[tbaher]

being behind a router

http://www.webopedia.com/TERM/N/NAT.html

[lizadonald]

tbaher, why our post has been removed from chit-chat to general gaming sub forum, are we playing any sort of game.