DNS setup with only one public IP - possible?

Hi all…

this one seems to be a bit tricky (if not impossible?!) and I could use some help and advise what to do.

Our server is currently hanging inside a small private LAN and our ISP assigned only 1 public IP to us. I am not sure yet if we will be able to get more, so I would like to see if I can get DNS up and running with only one (for now at least).

I know, DNS should have at least 2 IPs in 2 physical locations. I read that it is possible with 2 IPs pointing to the same DNS server, but could I just point ns1.mydomain.com & ns2.mydomain.com to a single IP as well!? Technically it does make no sense I am sure. :wink:


Nope, your registrar is not going to let that happen (they’d probably be in violation of an ICANN rule if they did). You need at least two IP addresses.

Realistically, you’re not going to have good luck running a server on a local private network. You’d be amazed at how unreliable most such service is (while colo and dedicated hosting providers measure uptime in number of 9’s, DSL and cable broadband folks measure it in hours per month…usually it’s orders of magnitude difference). I wouldn’t want to run a business on something that is unavailable for several hours every month. It’s fine for testing and development work…but when it comes time to launch it and let outside users bang on it, you’ll want something a bit more robust.

Joe you’re correct for half of that post :slight_smile:

RFC requires that 2 IP’s be used for DNS – ICANN couldn’t careless. There are a number of free dns hosting places such as xname, granite canyon, zoneedit, rollernet.us and so on… google is your friend on this.

As for DSL… phooy on you… I have a business DSL line here and my uptime for the last 6 months has been 100% unless it was downtime for maintainence.


well our server will not do any “real” business from this local network at this point. However, I wanted to host at least 2 private sites for now and have my DNS setup so I don’t have to fiddle much with it when moving the server later on to either a datacenter or our office. Is it possible to simply just change IPs for the whole thing using Webmin/VMPro at a later date, or do I have to set everything up again?


The ADSL line we are using right now is very reliable so far. Good up and downstream and over 95% uptime. Enough for me to host these 2 sites since they don’t need much bandwidth anyway.

Guess I will have to check with the ISP to get another IP for the time beeing. I have a suspicion they are not handing out more IPs, even for business ADSL lines like ours, because they don’t want people to setup DNS!? :frowning: Or I would have to check using a free service like zoneedit.com or such.

One thing I don’t get, how can I host ns1.mydomain.com on my server while the secondary DNS (ns2.mydomain.com) is hosted somewhere else? I mean how does such a setup look like? Won’t that be a problem for VMPro or Webmin?


Tony, hows it going? at one time i came accross the same question about setting up DNS useing 1 IP address, I went through the failures of trying to point ns1.mydomain.com and ns2.mydomain.com to the same IP addy and all that stuff, what i did in turn was i set my domain name to be hosted on the registrars DNS servers and just pointed the IP address for the everything, to my server, thus temporarly obsoleting the need to run DNS on my server, by temporarly i mean until i can get a second machine that i can run as a dedicated DNS server under another IP address, my parents are considering letting me run a DNS server under their address, my ISP allows me to have no more then 2 free IP address’ on my account, any more then that i would have to pay for.


I see your point… my problem is that I have 2 domains currently to be hosted on the same server. Using something like URL forwarding or such, not sure if thats a good solution?! Unless I would use a different port for one of the sites, or NAT. Any other idea what how I could solve this for now?


ps: I do have lots of trouble sending mails when using DNS setup with juust one IP. Seems most providers refuse to talk to my email server. :wink:

this is an easy one, currently i have 3 domains hosted on my server, 1 of them with a subdomain also hosted on the server, I have set them all up to respond to the same IP address on the same port, the only difference is that I have Apache setup to respond to domain names (default) so as long as you have the domain names configured on your server and ok’d by your apache configs then just point both your domains to the same IP address and port, when someone navigates to the server via a domain name apache will sort out the domains and do all the work :smiley:

Right, that’s about how I have it here now as well. I am using DNS from FreeDNS.org now. Setup there is a snap and really does not take long.

I figured as long as I have only these 2 domains running and VM does not have to setup any other domains for me, I am on the save side using a free DNS service.

But now I really would like to have at least one DNS server [primary DNS] running here as well. How can I have VM setup to use MY primary DNS while I am using a service like FreeDNS to host secondary DNS for instance!? Do I have to manually edit secondary DNS everytime I add a new domain or can I use Zone Transfers? How does that work exactly?

With other words: "How does outsourced/secondary DNS work with Webmin and Virtualmin Pro"?


Hey Tony,

With other words: "How does outsourced/secondary DNS work with Webmin and Virtualmin Pro"?

That depends on those services. Ideally, they would support zone transfers from your primary server. I’m guessing there are services out there that offer that, but I’m not familiar enough with any of the them to know. But that would solve several problems that folks often have running servers on a home or office broadband connection. You guys know better than me: Do any of the DNS hosts offer secondary service and allow you to configure them to be notified by the primary and receive zone transfers from them? That’d be nice, and I could add some documentation to that effect to help folks running Virtualmin on local connections (despite my belly-aching about it, we have a lot of folks doing so to good effect).

Howdy yall,
I have this same setup. I use Webmin-VM(GPL), with my own name server.
Then I use EveryDNS.net for my secondary DNS. It works fine!

I followed this guide posted here: http://beer.org.uk/bsacdns/
The only thing I changed was the “Also notify slaves…” my setup has 2 IP’s in this field.

"How does outsourced/secondary DNS work with Webmin and Virtualmin Pro"?
Very good, in answer to the question!


Great! Will check this out right now and let you guys know how it goes.


Well, seems I can not add my domain and IP on their site for some reason!? Adding just a basic IP works alright, but using their secondary DNS services seems to crash my browser all the time. Using Firefox and/or Safari.

Joe, there is one more thing I am very curious about. Would it be possible to have Webmin transfer all my new zones to a thirdparty DNS provider so that I would not have any DNS hosted on my machine at all or is that just another bad setup idea?


Joe, there is one more thing I am very curious about. Would it be possible to have Webmin transfer all my new zones to a thirdparty DNS provider so that I would not have any DNS hosted on my machine at all or is that just another bad setup idea?

Transfer, yes. DNS not hosted locally, no. Sort of.

It’s not a bad idea, but right now zone transfers to other servers is handled by BIND, rather than Webmin or Virtualmin. So, while it is possible to setup other servers as the only ones you use, the local machine still has to have a BIND instance running to ship off those details. Realistically, this isn’t all that big of a deal–the sum total benefit of not having BIND running is the recovery of a few MB of RAM (how big “few” is being a function of how many domains you’re hosting and some configuration settings).

There are some other things that Virtualmin expects to be true to enable a bunch of features related to the “how can I work on my site before the name has propagated from my registrar?” problem. In fact, Virtualmin now insists that you have as your first name server, or it’ll choke during config re-check. I’m not sure this is really the right solution to that problem, long term…but we had enough problem reports due to people not realizing that DNS takes time to propagate that we had to do something.

Long term, I suspect we will enable wholly remote DNS service…but, because zone creation is not standardized or accessible remotely, this feature will definitely require Webmin on the other servers. Maybe eventually someone will write plug-ins for some of the more popular hosted DNS services. The demand is pretty low for this sort of thing, so it’s not high on our todo list, though it is a pretty nifty trick for folks who host locally rather than in a data center.

Actually, now that I’ve rambled on a bit, doesn’t the DynDNS feature already support that? I’ve never used it, but I thought that was the point of it. Seems like that would be easy to modify to work with whatever DNS service you prefer to DynDNS.