Little help understanding some DNS...

[smids]

Hi guys (and gals),

I'm setting up a mailserver at home at the moment (purely for testing purposes, and to gain an understanding of all this stuff - please leave my ISP terms and conditions at the door ), however I seem to have hit a wall with dynamic DNS. My ISP doesn't offer static IPs.

Now, let me explain - I have a decent knowledge of networking and understand the basics of DNS etc. and if my IP was static, I wouldn't even need to ask this question, but alas it is not.

I've got an account with dyndns, but quite frankly, I'm a little lost as to how I set this all up.

My domain is registered with 1and1 and I obviously have control of the DNS for the domain, which I will call mydomain.co.uk.

The mail server is running on CentOS 5.1 and is a Scalix 11.3 mail server for which I'm hoping to setup IMAP etc. This runs on an internal DNS server which is built in. The IP of this machine is static at 192.168.1.75.

My main DNS server on my network is provided by another machine running W2K3. IP of this machine is static at 192.168.1.5, however I have a forward lookup setup on this machine which takes its DNS from OpenDNS @ 208.67.222.222.

Now, my understanding with dynamic DNS is shakey when it comes to getting the emails i.e. email @mydomain.co.uk to point to my home server's internal DNS (as that is what I am trying to achieve). Can someone help me break this down? I'm guessing I need to edit the domain DNS to point to my home server, so I setup a host on dyndns e.g. myserver.dyndns.org and this will update with my router which has been configured for the same. Then I changed the CNAME record of the domain (mydomain.co.uk) to myserver.dyndns.org - is this the correct method? Now what about the MX records on the domain DNS at 1and1? What do I need to do here?

I'm normally good at finding all this stuff out myself, but my brain is just a bit frazzled at the moment and someone who can break this down for me would be lavished with praise and gratitude. I have tried reading guides, but I must be having an off day.

Thanks in advance,

smids.

 

[atomiser]

i've done something sort of similar to this over the weekend. very 'ish', but i will try to help where i can!

you somehow need to get an 'a' record on your dyndns account such as mail.weirddomain.dyndns.com, the dyndns client either then needs to sit on your router or your server to keep the dyndns servers up to date with your current dynamic ip.

what i think you then need to do is setup an mx record with 1and1 that points to mail.weirddomain.dyndns.com.

that way when someone tries to send you an email they will find the mx record for your 'proper' domain, which will point to the 'a' record of mail.weirddomain.dyndns.com which will then resolve to the external ip address of your router.

forward the necessary ports on your router to the internal host on your network running the mail server and you may be in business.

i gave up trying to do this at the weekend and just upgraded my isp to static ip, registered my domain and setup the dns and mx record there. it cost me £5 for the domain for 2 years, and an extra 4 quid a month to upgrade from be* value to unlimited.

good luck!

 

[smids]

Right, that makes some sense.

So basically, I can use a hostname instead of an IP for an A record. I thought A records needed to be IP's - this may clear up all of my questions, should it prove to work...

Thanks, I'll give this a go.

Oh, and if only I could get myself a static IP. Damn Sky!!!

If I can get this thing going, you will be lavished with e-praise and lots of e-gratitude - not that this will actually amount to anything tangible for you .

 

[atomiser]

i dont think i've made myself quite clear...

let's say my domain is example.com, and my a records are www, mail, and vpn. these all point to my static ip address, as i only have one of them so i use port forwarding instead of a 1:1 nat on my firewall.

what i was getting at is that you somehow need to get the equivalent of my mail a record onto your dyndns domain... this way when your mx record says mail.something.dyndns.com it then resolves to your public ip so the mail transaction can take place...

this is what i was struggling with over the weekend which is why i just said sod it and got a proper domain and static ip (sorry, i know this doesn't help you!)

 

[smids]

Ah, now I get you.

So, to clarify, I would need to purchase a DNS service from dyndns, add my mx records and a records to their DNS, point my domain (mydomain.co.uk) nameservers to their (dyndns) DNS servers, which means that when someone types my domain, it will resolve on dyndns's DNS server, which will be updated with my current IP as that is the service they provide.

Or am I babbling like a fool?

Gawd, I really am having an off-day today.