Setting up own domain and mailserver

Paul A. Hoadley paulh at
Sun Feb 13 02:54:39 GMT 2005

On Sat, Feb 12, 2005 at 07:52:08PM -0500, RL wrote:

> 1. I have adelphia cable internet.  I would like to get a dyndns or
> account to have a static IP for my new godaddy domain.

I assume both of those services are dynamic DNS providers, and I'll
assume your cable provider gives you a dynamic IP address.  Dynamic
DNS providers don't provide you with a static IP, but rather
nameservice for your domain.  The provider will nominate some subset
of their nameservers for you to register (with the registrar that sold
you the domain name) as providing DNS for your new domain.  The idea
is that whenever your IP address changes, you contact the dynamic DNS
provider (in some provider-specific way---e.g., a web form, a local
script) to update your A record.

> Simple enough.  However, I would like to also do my own DNS to learn
> more about it.  Will I be able to do this if I set my nameserver on
> godaddy to my box's dyndns address?

Almost certainly not, for two reasons.  You need a static IP address
to lodge with your registrar.  (I guess it would be _possible_ to
manually update the address with your registrar every time it changes,
but quite impractical.)  Further, you need to provide at least two
nameservers for your domain.  Again, it is _possible_ that you could
personally provide one, and use a DNS provider as a secondary.

> 2.  What about reverse DNS?  Could I possibly do that on my box?  

Not unless you solve all of the problems above, and then discuss the
issue with your ISP---since they own the IP address, they run the
corresponding part of the zone, and the specific PTR
record you will require.

> 3. I would also like to run my own mailserver for that domain (again
> to learn).  Would I be able to do this and send receive email
> from/to name at

This you'll be able to do.  You need to add an MX record to your zone
file at the dynamic DNS provider.  You would want mail sent to the
host named in the A record.

> I know most ISPs block port 25 and has a pay service
> called mail reflector that can get around this.  Is this necessary?

If _your_ ISP blocks port 25, then you'll have to do _something_ to
get around that, but I don't know if that particular service is the
right solution.

> Why couldn't I just set up sendmail to use a port other than 25 like
> 8080?

There's certainly nothing _intrinsically_ special about port 25.
However, it's the port that everyone's agreed to send mail to.  If
your sendmail was listening on port 8080, how would my sendmail know?


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