Mac mini server networking and DNS setup help

Question

Thanks in advance to anyone who can help me with this. I'm working at a small business where I'm the only guy with any IT experience at all, but I'm new to Macs and OS X (<1 year) and being a server admin so please bear with me.
We just bought a Mac mini server as we are expanding from a bunch of workstations and Google Docs. I've just gone through the installation process, but nothing else is on the server, no user data at all, so if the answer is to reinstall from scratch, I can do it.
We'd like the mini to be a file server, print server as well as the gateway for the internet. I realize we could stick to our router and have the server as another node in the network, but we also got a Time Capsule for backing up the server and will locate it in another room to be another wireless access point there.
When going through Server Assistant, I didn't really know what to name the machine so I used corp-Server.local for the Current Hostname and corpserver.private for the DNS Hostname (though i actually use a 3-letter company acronym instead of "corp").
However, i realized after setup we'd want to access the server externally by name, so I changed the DNS hostname to server.companyname.com in the Zones tab of the DNS section of Server Admin (edited primary zone name, changed Nameservers entry for both primary and reverse zone).
I don't know what else I need to do though because there are loads of instances where corpserver.private still shows up, like in the Open Directory section of Server Admin (which btw always hangs when I open it) and the Contact Info of users (eg. user email is [email protected]). I also had trouble earlier using Server Preferences and Server Admin either not connecting or not recognizing my login, but that seems to have abated.
I guess my problem is, where else do I change the DNS hostname? Or do I have to change the DNS hostname back to corpserver.private (in Server Admin)? That way, I think at least everything will be consistent, but would I be able to still configure it somehow so that externally, we could access the server by the server.companyname.com URL?
Also, can the mini be a wireless router for the office? As mentioned before, we want to cut the existing wireless router out and use the mini instead (and use the Time Capsule as a wireless bridge).

Answer 1

So the ISP<->router connection can have a dynamic IP address, but the router<->server one should be static? I guess that means I have to set the IP address in the router. I hope I can get access to it. I don't suppose it matters which one I set first?
An IP router does not assign addresses.
A DHCP server does assign IP addresses upon receipt of a DHCP request from a client.
Some routers (and many firewall routers) do include a DHCP server.
A box with a static IP address does not need to send a DHCP request; it has a static address.
You'll need to ensure that the IP address pool within the DHCP server does not overlap the addresses that are manually assigned to your local hosts; the static IP addresses on your LAN.
[Here is an overview of the pieces involved here, and some of the typical terminology|http://labs.hoffmanlabs.com/node/275].
I hate to belabour the point, but I just want to clarify: in my setup where ISP<->router<->server<->clients, where the server is the only machine connected to the router, which one should be the local DNS server? The server, right? So if the DNS server is turned on in the router, I should turn it off? Or do I need both (ie. router for its LAN (to server), and server for its LAN (to clients))?
So to confirm, the configuration includes (probably) a modem, a router (firewall) and a router (Mac), and then the rest of the (local) show? That is not the simplest configuration, and it's Particularly given that Mac boxes make expensive and slow routers.
The usual configuration is ISP>firewall>LAN and the LAN is usually built from WiFi, wired connections and switches. Within one subnet (which is typical) any host inside your firewall is connected on the LAN, and can communicate (directly) with any other LAN client. The firewall is configured as the gateway; that's the default route for outbound connections.
One more thing that's bugging me: I still don't understand why I couldn't connect to the internet when I plugged in the Ethernet cable from server to router. Even if I was using DHCP to get a dynamically allocated IP, shouldn't it still have worked? I'm worried that I'm going to set up everything as it should be but the connection still won't work.
That's likely because you're trying to use the Mac as a router, and that takes specific configuration steps. It's easier to have ISP>firewall>LAN, and have the Mac OS X Server box and the rest of the stuff as peers on your LAN. If you really want to use the Mac as an IP router, look around for setting up static routes on Mac; there are postings around for that.
If your data is more valuable and your security preferences and requirements are higher, then you may want a firewall with a DMZ, and put your web-facing boxes over in the DMZ. If you're serving stuff to the web or a mail server or such, it's possible to get breached, and a breach means folks can potentially get further into your LAN. With a DMZ, they're somewhat more isolated from your LAN.