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  • From: "Shea Tisdale" <shea AT sheatisdale.com>
  • To: "'Internetworkers: http://www.ibiblio.org/internetworkers/'" <internetworkers AT lists.ibiblio.org>
  • Subject: RE: [internetworkers] Things that make you go hmmmmm?
  • Date: Mon, 20 Oct 2003 09:37:43 -0400

Steve, I've never heard of this happening when the records are entered
correctly. If this occurred and can be corrected in an hour, it is a
mistake on the part of your host/ISP.

I don't know your level of understanding DNS, so please forgive if you
already know this. But here is a very simplified version of how this
part of DNS works.

Two things are important here: 1. DNS is method by which an easy to
remember name can be translated into the hard to remember IP address.
2. DNS is a distributed system for maintaining all the records of all
the domain names.

So, when you register a name such as xyzcorp.com, NetworkSolutions
enters that into the Top Level Domain registry or TLD. That record says
your name exists and points all inquiries to the IP address of a set of
servers that have Authoritative control for your name. This setup lets
xyzcorp or their host/ISP have authority over the xyacorp.com domain and
all the tens, hundreds or thousands of machines using that domain name.
That way they don't have to get NetworkSolutions to make all the DNS
entries or changes for all their machines and every DNS server doesn't
have to store every single record for every machine on the Internet.

So when you create mail.xyzcorp.com or www.xyzcorp.com, the DNS record
and IP addresses for those machines aren't stored in the TLD servers,
it's stored in the DNS servers at your company or your host/ISP.

In practice here is how it works. When I type in www.xyzcorp.com into
my web browser, my machine asks my local DNS to lookup the address. It
effectively goes out to my local DNS server and says, "Hey, I need to
know the IP address for this domain name."

My local name server may already know the IP address for www.xyzcorp.com
That would be the case if I was also on a machine at xyzcorp.com or if
another request to resolve that name had come in recently (name servers
can cache IP addresses to speed things up). In either case, the name
server will return the IP address immediately. Let's assume, however,
that I'm not at xyzcorp.com and that the name server hasn't cached the
record.

So I'm at my house, using my machine. And I type www.xyzcorp.com into
my browser. My machine asks my local name server for the IP address of
www.xyzcorp.com. My local name server would then start its search for
an IP address by contacting one of the TLD or root name servers. The
root servers know the IP address for all of the name servers that handle
the top-level domains. My name server would ask the root for the
www.xyzcorp.com, and the root would answer by providing the IP address
for the name server that is authoritative for that domain.

My machine would then contact the authoritative domain name server and
be provided the appropriate IP address for www.xyzcorp.com. My machine
would then connect my browser to that IP address.

Therefore, anything that has happened such as the name being kicked out
of DNS, etc. is at your ISP/Host.




> -----Original Message-----
> From: internetworkers-bounces AT lists.ibiblio.org
[mailto:internetworkers-
> bounces AT lists.ibiblio.org] On Behalf Of Steve Steele
> Sent: Monday, October 20, 2003 8:31 AM
> To: internetworkers AT lists.ibiblio.org
> Subject: [internetworkers] Things that make you go hmmmmm?
>
> Has any one ever heard of this or is my tech support in a
> round-about way saying, he doesn't have a clue what happened?
>
> Two of my client's web sites have come up page can't be found.
> According to my hosting company. They said that the DNS had
> been kicked out for some reason and that they have updated the
> records and will be about an hour for the update to take.
>
> So I'm just curious, how does a domain get moved out of the
> DNS registry? Has this ever happened to anyone. I'm wondering if
> something more nefarious is at hand. Some "A" hole hacker just
> having fun.
>
> Any ideas?
>
> Me!
> ---
> Come and play at the InterNetWorkers Web site!
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