What is ping?

ivj · 07-18-2005, 03:43 PM

I had a few questions about pinging...

When I use ping google.com it tells me that time is around 80 milliseconds...

Is that the time for the signal to get to google, or is it time for a signal to get to google AND come back?

Technically, shouldn't the speed TO google be different than the speed FROM google, or should it be the same?

Also, whats TTL (time to live)?

Thanks!

leonscape · 07-18-2005, 03:47 PM

OKay ping is a way of measuring the speed of 'reply' from a server. That is the response time. How quickly a ping packet got to the server and the reply came back. Usually done in groups so you can get an average. ( as it will vary depending on what route each packet took ).

The TTL is how long each packet is allowed to live, i.e. how long before you'll wait for a response before giving up ( think of it like a timeout ).

ivj · 07-18-2005, 03:50 PM

Oh wow so you're saying that when I do ping google.com and it tells me 80, what happened is that it took about 40 ms to get to google and about 40 to get from google to me?

And is 1:1 ratio correct? Or will sometimes one be slower than the other? And if so, is there any way to measure it?

leonscape · 07-18-2005, 04:01 PM

Yes sometimes, it will be slower one way or the other, but probably not by much, also it depends on how quick the server is, Google having lots of power and badwidth, responds to the ping request really quicky.

So its Time to server, server speed in responding, and time back.

Theres no easy way to say how long it took one way or the other, as that would require both your machine and server agreeing on eactly what time it is within milliseconds.