How do these speed tests work?

Office_Shredder

I was wondering... if you have DSL or cable, but your router can only transfer at 56 kbps, if you go to one of those websites that tests your internet speed will it return 56 kilobits per second or the megabits per second that your actual broadband line gives?

MATLABdude

I believe that these work purely by throwing data at you, and seeing how long it takes for you to get them, and send something back. (Also, usually measurements on latency, and how many hops it takes to get data from them to you and vice versa).

So going to a website like SpeedTest (www.speedtest.net) returns you different results depending on which server you click on, what time of day it is, how things are being routed, or even whether your neighbor is downloading something. Outside of looking up the specs for your modem (by this, I mean ADSL or cable--probably not too many of the voice variety these days), I don't know if there's a way to (easily) measure speed.