FAQ - frequently asked questions

the basics

What is DDNS?

Dynamic DNS, in a nutshell; a way to keep a DNS hostname pointing at a dynamic IP address

How much does it cost?

Nothing, at least for the provided 'core' domains and 'shared' domains, but shared domains have some pitfalls, read on.

How does it work?

A lengthy answer; our servers keep a record of your IP in an object we call an 'IP-Handle', we also know what hostnames you have chosen, we call them 'DDNS-Records', all of this information is exported by our DNS servers to the global DNS. The nice part comes when your IP changes, all you have to do is change your IP-Handle to match the change and all of your DDNS-Records will follow.

How do I use the client?

Take a look at this short excerpt from an email I sent answering this question.

I have to register to use ddns.nu, why?

House keeping. In particular for your own security we need an identity which 'owns' all your DDNS-Records and IP-Handles (and perhaps Domains). We ask only for you full name and email address, you can pick your own username and password. Optionally you can supply your telephone number for rapid contact, but it is not required. Your email address is required for administrative contact, especially if you use shared domains.

Do I own my hostname?

No, not in the sense of a domain registration. The ddns.nu site owners are the registrants of the 'core' domains, and have full naming control over them, our decision is final, we reserve the right to delete records, etc. Don't let this concern you too much, unless you delete your usage of a record no one else can steal it from you (except us :), and unless we receive a complaint we won't censor records.

The situation is more complex for 'shared' domains as we don't own them either. In this case, the owner of the domain has the right to administer the namespace how they see fit. We are a hosting proxy in this situation and only offer basic double-blind services to arbitrate any disputes.

This is not ment to discourage 'shared' (or donated as some call them) domain use, but I would think twice about using them for anything mission critical as the owner has the right to pull them at any time. We do ask the shared domain owners to give a grace period if they intend to pull a service or redelegate the domain, but have no power to enforce it.

Caveat Emptor. You have been warned!

Where do I start?

1. Register yourself with the site
2. Login as the new user account
3. Create an IP-Handle in the maintain page (type a name for it, correct/enter the IP, click Add-Handle)
4. Create a DDNS-Record using the same page (once you add a handle you'll be able to make records)
5. You would be all set now, in about 15 minutes or less the hostname(s) (DDNS-Records) you have made should be available
6. At this point you might like to grab one of the remote update clients. This is optional, you can just as easily use the site to update handles

What is IN A and IN MX?

An IN A record is a hostname to IP mapping. This is the most common form of DNS record, and the type you want for making yourhostname.cable.nu point to your IP.

An IN MX record is a hint to mailservers as to where it should send email for a domain. This is the type of record you want if you are running a local email SMTP server. If you don't need email, don't use it, it is not required and can cause more harm than good.

What is this Pri thing on MX records?

This is the priority or prescedence of an MX record. If more than one MX record is present for a domain, they are searched in order of increasing value by this number. The first server that answers is given the email. Unless you have multiple mail servers, you don't need to worry about this.

What does the expiry value mean?

This is the time-to-live given out by the DNS server for the record in question. Basically it is how long a remote DNS server may cache the result of a lookup on this record, or how long incorrect information may be visible after a change.

The correct choice for this value is complex. A good rule of thumb is a day for static IPs, an hour for stable connections like cable, 10 minutes for xDSL or similar services, and a minute for dialup and other rapidly changing IP connectivity. Needlessly low values just slow lookups and cost us money, high values will mean that wrong data can take a while to get flushed, stick by the numbers above and you'll be fine.

commercial service ('private' and 'shared' domains)

Can I use my own domain?

Yes. There are two options.

'Private' hosting, which enables only your account to access the domain namespace. This is the option most people choose who want to use the domain commercially. It works just like a 'core' domain, but you own it and no one else can see it in the maintain page. It has some additional features over 'core' domains (domain IN A and MX records) which have a slightly different interface.

'Shared' hosting is the alternative. It is cheaper, but allows all ddns.nu users to create records in your domain's namespace if they wish. You still retain full control of the namespace, we mearly supply the hosting service, you administer.

How much does it cost?

Private Hosting: $10 australian per month per domain
Shared Hosting: $25 australian per year per domain

Where do I delegate to?

We'll supply that information when you register for the commercial service (either 'shared' or 'private'). The basic commercial registration process is:

1. Register a normal ddns.nu account
2. Play with a free 'core' domain to get an idea if this is what you need first!
3. Register the domain of your choice anywhere you like (we are not a registar, but we can help if required, we are not the cheapest though)
4. Email the admin people here, including details of the domain you'd like to setup
5. We'll reply giving the delegation details and asking for payment details
6. Delegate your domain to our name servers, and arrange payment.

Why isn't shared hosting free? After all we are loaning our namespace to you.

The fee, which is very small, just over $2/month, covers our infrastructure costs. It is your rent for the bandwidth, time, and effort that goes into providing the hosting. This discount (20% of the full private hosting fee) is our thanks for helping make ddns.nu so sucessful. We prefer to think of it as you loaning the ddns.nu community your namespace, rather than you loaning it to ddns.nu.

our technology

Will you licence it to me?

Why would we need to? The shared domain lets you be your own DDNS provider, albeit under our branding. We are open to enquiries, but ddns.nu is not about profit, if we make enough to pay for our DNS request traffic we are having a good month.

Can I write my own client?

Yes, and we encourage it. The protocol spec is open, and there are two reference implementations available, one C and one Java. If you do make one, we'd love to know about it, so we can tell all ddns.nu users about it. We don't mind if you make it commercial, or build into into a commercial product, just remember to mention us in there somewhere :) (not that the client is much good without a server and the rest of ddns.nu)

What about RFC compliant DNS update messages?

Currently there is no standard for secure updates. Several recent DHCP implementations support 'true' DDNS, but not of sufficient security to be used outside of LANs. If this comes along, there'll be a ddns v4 released. At present we just ignore the reject messages scrolling by in the logs.