Domain names cost money if that’s your question. If not then you’re going to have to be more specific.

If you’re not running your own DNS then I’m not sure what it is you think you need to put a domain name into. What are you talking about and does it actually have anything to do with OS X Server?

What do you want to accomplish with the dyndns registration? Do you plan on running some services like a website or email or ftp or jabber and you are looking for a way to locate your machine “from the outside” since your ip changes at will? If that’s the point then it’s not 100% necessary to have your own internal DNS service since you aren’t going to be authoritative for the “dyndns.org” domain anyhow. It’s totally fine to continue to use your ISP’s DNS servers.What ever the internal hostname or domain name you setup your Mac OS Server or client really has no relation on the dyndns name. Internally your computer could be configured as foo.bar.org but your dyndns name will be foo.dyndns.org or even something unrelated like snafu.dyndns.org. Internal and external name can be different. If you have internal DNS setup nobody from the outside will ever query it looking for your computers dyndns.org name. They will always be looking to the authoritative dyndns servers which from my last query are:

dyndns.org. 86400 IN NS ns1.dyndns.org.
dyndns.org. 86400 IN NS ns2.dyndns.org.
dyndns.org. 86400 IN NS ns3.dyndns.org.
dyndns.org. 86400 IN NS ns4.dyndns.org.
dyndns.org. 86400 IN NS ns5.dyndns.org.

Hope that makes a bit more sense. If you are looking to setup some very DNS centric services like Open Directory, internal DNS becomes required but still doesn’t change the fact that your external hostname can be different than the internally used one.

-jerky

I get Mactroll’s concern now. If you aren’t running your own DNS your ISP’s DNS will give resolve to the external address which could make it difficult to access the hostname internally.

jerky

It can be done but if you’ve never worked with a lot of the software it can be a bit intimidating. It’s a lot to grasp. You will need to setup internal DNS first in order to get OD working. You internal domain name could be anything you want to call it we’ll say example.com. so your fully qualified name internally will be server.example.com. You probably should avoid using an existing name like apple.com.

Since you are going the free route and have registered tmac.podzone.net you computer will essentially have two names an external and internal name. You will need a DynDNS client that can grab your external IP from the firewall. I’m not sure if the simple GUI one will do that. I had played with ddclient which was a perl script client.
It’s been a while so there might be some better options available now.

Since this sound like the first time you are tackling setting up some of these services, I would focus getting the various services you want to use working internally first and then move on to DynDNS after. Baby steps is the way to think of it. Get DNS working, then OD. then move on to say the fileserver and webserver until you are happy. Once you are satisfied with it’s internal operation, you should be ready to enable access to the outside. That’s when I would start looking at the dyndns configuration.

jerky

What you need is a split-horizon DNS setup. Like jerkyjerk said, you should set up everything internally first and then poke holes in your NAT to allow certain things to come in from the outside.

Step 1: Set up your router
Assuming you’ve got a simple home router that does NAT and creates an internal network in the 192.168.1.x range and that its internal IP in 192.168.1.1… Log into it and turn off its DHCP server.

Step 2: Set up your server network settings
Static IP address: 192.168.1.2
Subnet Mask: 255.255.255.0
Router: 192.168.1.1
DNS Servers: 192.168.1.2 (Don’t list any others)
Search Domain: tmac.podzone.net

Step 3: Turn on it’s DNS server
Create one Primary Zone called “tmac.podzone.net.”
Make sure there is an entry for “myserver” which maps to 192.168.1.2
Also create a machine record for “router” which maps to 192.168.1.1
For good measure, add entries for all of your computers and give them IPs.

Step 4: Turn on it’s DHCP server and set it like:
Starting IP address: 192.168.1.100
Ending IP address: 192.168.1.200
Subnet Mask: 255.255.255.0
Router: 192.168.1.1
DNS Servers: 192.168.1.2 (Don’t list any others)
Search Domain: tmac.podzone.net

Go around to all of your machines and collect their MAC (ethernet) addresses. Enter each one into the static maps so that they will always get the same IP from your DHCP server (and it will be mapped to the right hostname by your DNS server).

Now you should have working forward and reverse DNS on your internal network. Each machine is looking to your server for DNS, so it’s like their own private club where they all know each other’s names like foo.tmac.podzone.net. Similarly, outsiders (who aren’t using your DNS server) won’t know their names, and won’t be able to connect to foo.tmac.podzone.net. With this, you should have no trouble setting up other services like OD, AFP, etc. for your internal computers.

We still haven’t done anything about external access. DynDNS is mapping tmac.podzone.net to your external IP… something like 24.17.26.164 maybe. This IP is actually pointing to your home router from the outside. You can log into your router and set up port forwarding. Forward port 80 to 192.168.1.2, and anyone going to http://tmac.podzone.net will get the website hosted on your server. The problem is that accessing http://tmac.podzone.net may or may not work, depending the way the NAT in your home router works. To fix this, you need to add a record to your internal DNS server to make tmac.podzone.net to map to 192.168.1.2.

This is the “split” of split-horizon. You have a single FQDN of “tmac.podzone.net” which resolves to 192.168.1.2 for your internal computers, and 24.17.26.164 for the rest of the Internet.