[PLUG] Victor is trying to understand DNS

Bill Barry bill at billbarry.org
Sun Oct 14 16:28:57 UTC 2007


On 10/14/07, Ed Sawicki <ed at alcpress.com> wrote:
>
> Victor's not wrong. A DNS nameserver can resolve an IP address
> to a name as well as the reverse. It's just that resolving a
> name to an IP address is more common.
>
>
> Ed
> _______________________________________________


Reverse DNS, i.e. resolving an ip address to a name is as far as I
understand a slightly different process than regular Forward DNS. It
is indeed handled by nameservers, but  via a different route. If the
ip address is a.b.c.d. It looks up a PTR record in the domain name
d.c.b.a.in-addr.arpa.  The control of these different routes is in
different hands.

 When I register a domain, I have control over which IP address  that
domain name points to. I tell the domain name registrar the
nameservers I will be using for that domain and I tell the nameservers
which IP address I will be using for that domain by creating an A
record.

I do not have the same control over the reverse DNS. That control is
in the hands of the ISP that gave me the address. If I want to have
the reverse DNS work correctly I must get the ISP who gave me the IP
address to change the PTR record  which points from an IP address to a
domain name. They control it, not me.  Can they delegate that
authority to me? How do they do that?

Since I have never done this, the questions are. Is all of this
correct? If so how do you go about setting up Reverse DNS.  Do you
just email the ISP and ask them to do it or is there some other
mechanism?

Thanks,
Bill



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