Dynamic DNS question

[tYY]

Hi,
I'll soon buy a domain name; let's say "dom.fr". My IP is changing once
in a while, so I'm currently on DynDns; let's say "dom.dyn.net".
So far:
- I am m...@dom.dyn.net,
- my web site is http://dom.dyn.net/,
- my XMPP server is dom.dyn.net, and so on.

I was hoping to just "replace" dom.dyn.net with dom.fr.

But a quick search on the net seems to imply that I won't be able to do
that, because I'll actually have to update the dyn IP on a subdomain, so
that I would be:
- m...@mail.dom.fr, not m...@dom.fr,
- and the web site would be http://www.dom.fr, not http://dom.fr :(

Can someone confirm that?

I'm not really sure how things will work (I don't know much about DNS).
I understand that there are two routes available to me:
-1- either "dom.fr. CNAME dom.dyn.net.",
-2- or "dom.fr. A 12.34.56.78" with a script on my side that would
update this record whenever the IP changes.

I understand also, that not everything is possible, due to DNS update
times...
For some reason, my searches seem to say that route -1- is not possible
on "dom.fr", only on "something.dom.fr" :/
And for some reason, (eg.) OVH only provides the route -2- feature on a
subdomain :/ Why? I don't know...

[Barry Margolin]

In article <l74k96$6v4$1...@speranza.aioe.org>, tYY <ne...@yeti.selfip.net>
wrote:

> Hi,
> I'll soon buy a domain name; let's say "dom.fr". My IP is changing once
> in a while, so I'm currently on DynDns; let's say "dom.dyn.net".
> So far:
> - I am m...@dom.dyn.net,
> - my web site is http://dom.dyn.net/,
> - my XMPP server is dom.dyn.net, and so on.
>
> I was hoping to just "replace" dom.dyn.net with dom.fr.
>
> But a quick search on the net seems to imply that I won't be able to do
> that, because I'll actually have to update the dyn IP on a subdomain, so
> that I would be:
> - m...@mail.dom.fr, not m...@dom.fr,

That's not necessary. You should have an MX record:

dom.fr. IN MX 10 mail.dom.fr.

Then use dynamic DNS to update the A record for mail.dom.fr.

> - and the web site would be http://www.dom.fr, not http://dom.fr :(
>
> Can someone confirm that?
>
> I'm not really sure how things will work (I don't know much about DNS).
> I understand that there are two routes available to me:
> -1- either "dom.fr. CNAME dom.dyn.net.",
> -2- or "dom.fr. A 12.34.56.78" with a script on my side that would
> update this record whenever the IP changes.
>
> I understand also, that not everything is possible, due to DNS update
> times...
> For some reason, my searches seem to say that route -1- is not possible
> on "dom.fr", only on "something.dom.fr" :/

That's correct. You can't have a CNAME on the zone apex.

> And for some reason, (eg.) OVH only provides the route -2- feature on a
> subdomain :/ Why? I don't know...

There's no DNS-based reason why they shouldn't allow dynamic updates of
the A record on the zone apex. This is a restriction your DNS provider
is adding on their own.

--
Barry Margolin, bar...@alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***

[tYY]

Le 27/11/2013 16:24, Barry Margolin a �crit :

> In article <l74k96$6v4$1...@speranza.aioe.org>, tYY <ne...@yeti.selfip.net>
> wrote:
>
>> Hi,
>> I'll soon buy a domain name; let's say "dom.fr". My IP is changing once
>> in a while, so I'm currently on DynDns; let's say "dom.dyn.net".
>> So far:
>> - I am m...@dom.dyn.net,
>> - my web site is http://dom.dyn.net/,
>> - my XMPP server is dom.dyn.net, and so on.
>>
>> I was hoping to just "replace" dom.dyn.net with dom.fr.
>>
>> But a quick search on the net seems to imply that I won't be able to do
>> that, because I'll actually have to update the dyn IP on a subdomain, so
>> that I would be:
>> - m...@mail.dom.fr, not m...@dom.fr,
>
> That's not necessary. You should have an MX record:
>
> dom.fr. IN MX 10 mail.dom.fr.
>
> Then use dynamic DNS to update the A record for mail.dom.fr.

Thanks for the tip, I'll keep that in mind.

>> - and the web site would be http://www.dom.fr, not http://dom.fr :(
>>
>> Can someone confirm that?
>>
>> I'm not really sure how things will work (I don't know much about DNS).
>> I understand that there are two routes available to me:
>> -1- either "dom.fr. CNAME dom.dyn.net.",
>> -2- or "dom.fr. A 12.34.56.78" with a script on my side that would
>> update this record whenever the IP changes.
>>
>> I understand also, that not everything is possible, due to DNS update
>> times...
>> For some reason, my searches seem to say that route -1- is not possible
>> on "dom.fr", only on "something.dom.fr" :/
>
> That's correct. You can't have a CNAME on the zone apex.
>
>> And for some reason, (eg.) OVH only provides the route -2- feature on a
>> subdomain :/ Why? I don't know...
>
> There's no DNS-based reason why they shouldn't allow dynamic updates of
> the A record on the zone apex. This is a restriction your DNS provider
> is adding on their own.

OK, this confirms what I deduced from other sources. It seems I'll have
to buy my domain name somewhere else, or at least find a free DNS host
that will allow me to programatically update the A record of the zone apex.
Thank you Barry!