Re: [MLUG - DISCUSSION] where is www.amazon.com?

[Stephen Montgomery-Smith <EMAIL:PROTECTED>]

Mike Miller wrote:
> On Fri, 2 Mar 2007, Spurling, Shannon wrote:
>
> > Yeah, but that did happen before...
> > If the distributed caching server company has a glitch, it could be that
> > they can't serve the name. When the original post hit the list, were you
> > both still having trouble? I looked it up, and it worked fine for me.
>
>
>
> The problem persisted for awhile after I sent my message, but I don't 
> know when you saw it.
>
> I guess someone out there made a fairly significant job-terminating kind 
> of mistake.  If people can't get to www.amazon.com, that's costing 
> Amazon some serious money.

Based upon Shannon's analysis, I think that it is more of a temporary 
glitch than anything else.

If you use "dig" instead of "nslookup" it gives quite a bit more detail, 
some of which I must admit that I don't understand.  But I think it 
provides a nice explanation.  Let me explain DNS as I understand it.

When you send a request to you DNS server, it first looks in it's cache 
to see if it already there.  If not it looks around on the internet. 
First it goes to a .com server to look up amazon.com.  If the .com 
server is up, then you will already have the answer to amazon.com.  But 
if you want www.amazon.com, then it has to go to the .amazon.com DNS 
server to look up the www.  So if the .com server is up, but the 
.amazon.com server is down, then you will get the phenomenum you 
experienced.

However, the problem might not be that the .amazon.com server is down, 
but rather that the connection to this server is temporily down.  I find 
that this happens intermitantly all the time on the internet.  This 
would not qualify as a job terminating mistake.

And if you use the "dig" command, it tells you the server - the 
"authority section" where the info originates.  The neat thing about 
this is that if amazon.com decided to change what www.amazon.com is, 
they change it on their own server.  Then as DNS server chances around 
the world expire, they upgrade their DNS entries as required.  In fact 
we experienced this at MU - we changed the IP numbers on computers in 
the math department.  All that MU had to do was change their DNS entries 
on their own DNS servers, and voila, they have changed all over the 
world within a matter of hours if not days.

Hopefully Shannon can correct me if I am wrong.


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