Setting up own domain and mailserver

Luke luked at
Tue Feb 15 04:57:09 GMT 2005

I was hoping somebody more knowledgable than me would answer your 
questions.  Maybe than did and I lost it in all the spam.
I've been intrigued by these same topics for awhile and I've learned a 
little bit.  I'll share what I've figured out below.

On Sat, 12 Feb 2005, 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.
> 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?  And from there can I set up A
> records, MX Records, etc and all that good stuff?

For a domain name to be effective, you need a public and highly referenced 
source to map your name to your IP address.  That's what these public 
registrars do.  You want them to map your name to your address.  You can't 
move that service to your own box because... well.. how would anybody find 
you in the first place?
Technically you can do SOME of the domain service yourself if you're 
running a network.  Public DNS servers might get them to, and then you could direct them to,, etc.  but you probably don't have any need for 
something like that at home.
You can run your own DNS service to do lookups for yourself though, and 
it's a fun way to learn about how the global system works.  Check out the 
sections of the FreeBSD Handbook on BIND.  Running DNS for a small network 
in my home was pretty educational for me.

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

It's possible to have any number of names pointing to a single IP address, 
but that IP address is only going to reverse-map to one name, and that 
name is going to be one of Adelphia's names I'm afraid.

> 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  I know most ISPs block port 25 and
> has a pay service called mail reflector that can get around this.  Is
> this necessary?  Why couldn't I just set up sendmail to use a port
> other than 25 like 8080?

Sending isn't the problem.  You can send from just about any port you 
want.  It's receiving that's the problem.
When a mail server tries to deliver mail to, it's going to 
be looking for your mail server on port 25, because that's the standard. 
It's just like how your web browser always goes looking for a web server 
on port 80 when you contact another machine.
Unless there's some trick you can do with the MX records for your domain 
to advertise to the world that your mail server is running on a 
nonstandard port, I don't know how you could get around the receiving 
problem if your ISP blocks incoming connections to port 25, short of 
having some external service like those you've mentioned cache the mail 
for you.

I'm no expert - just somebody who's spent some time fooling around with 
this stuff.  If I've told you anything wrong, hopefully somebody will step 
up and correct me.

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