Non-existant URLs

[aatcbbtccctc at yahoo.com]

Hi folks

Say I type a non-existant URL; for example,
"http://www.jksfdjiteui4wtknfsjkfzuisfz.com".

When I do that, from a PC in Australia, I get an instant error that the
URL does not exist. The delay is imperceptible. I feel that there has
not been enough time to send a query right back through to a root
server.

So, how is it /known/ that the URL does not exist? Or am I wrong in
assuming that a query right back through to a root server, should take
at least a few seconds?

TIA,
TC