[TriLUG] Questions on dyndns.org

[Mike Mueller]

On Thursday 03 October 2002 16:22, Jeremy Portzer wrote:
> On Thu, 2002-10-03 at 15:39, Jeremy Portzer wrote:
> > You may want to read a refresher on how DNS and TCP connections work in
> > general.  Remember, DNS is like a telephone book.  Suppose that you look
> > up a phone number in the book, and make a phone call.  You get a
> > recording that says to use your fax machine to connect instead.  The
> > phone book cannot possibly be "redirecting" you to your fax machine.
> > The phone book is only listing telephone numbers!  The recording at the
> > other end of the phone line is doing the redirection.
>
> On further reflection, let me clarify my analogy.  Suppose that you look
> up a company in a telephone book, and place a call to the listed
> number.  Then, you get a recording that says, "Use your fax machine, and
> call this other number."  The recording is giving you two things -- the
> new number to call, and the new way to connect (fax instead of voice).
> The recording is providing the "redirection," sending you to a new
> number (IP address) and telling you about a new way to connect (new port
> number).
>
> The above analogy could actually happen, if the company changes their
> fax number often, so they don't publish it.  But suppose they always a
> 1-800 "redirection" number.  Clients just need to call the 1-800 number
> (contact the DynDNS web application) every time to get a fax number (IP
> address).
>
> Normal dynamic DNS (as opposed to port redirection) would be the
> equivalent of a standard 1-800 fax number, for which the "destination"
> phone number is unknown (and usually hidden).  When the phone number
> changes, the business updates their 1-800 service company with the new
> destination number.   But the method of connection (fax) is always the
> same.
>
> For port redirection performed by a NAT firewall, you could try using
> the analogy of the teletype relay service that's used by the deaf.  See,
> analogies are fun. :-)
>
> --Jeremy
>
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-- 
mueller, mike

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