Dynamic DNS Theory of Operation
1. Introduction
1.1. What is Dynamic DNS?
If you have made it this far, you probably have some idea of what dynamic DNS is. This document should help you learn more of what exactly it is, what it can do for you, and how it works.
So, back to the main question. What is Dynamic DNS? Simply put, dynamic DNS allows a user to have a static hostname that changes which IP it resolves into fairly dynamically. The details of this are explained in further detail below.
DNS stands for Domain Name Service and is how a name like www.geeksanon.ca turns into the actual Internet address (IP address) that your computer connects to. These addresses are (supposedly) guaranteed to be unique across the entire Internet. The address is something such as 216.123.201.9. This number is the physical number that one computer needs to contact another. So, what DNS provides is the ability to use a name (called a domain or host name) to find the Internet (IP) address of a computer.
1.2. Why would I use it?
On the Internet, a number of Internet Service Providers (ISPs) provide an IP address that changes from time to time. It may change every time you connect to the Internet, or it may change only when the ISP makes changes of some type. The average time that an IP address is assigned to a specific computer can range anywhere from a few minutes to months or years on end. This service is primarily targetted at users who use dialup, cable, or DSL. Most ISPs that provide these services change the IP address of a connecting computer fairly frequently. Dialup is the most frequently changing one of the group. The address tends to remain assigned to your computer until you disconnect in some fashion from the Internet (turning off your computer, hanging up the dialup connection).
What dynamic DNS can offer you is the ability to have a host name that points to your most recent IP address at any time. This host name will allow you to try out things that need a host to connect to, or when you wish to be known by a constant name on the Internet, instead of having to tell people your new IP address every time you connect. It is even handy for people that have IPs that very rarely change, but are still retrieved from a service like DHCP. It will let the user update the host name record to point at the new IP address as soon as the new address is put in place, letting a user get in to their machine remotely (if it is setup to do so), or provide web services, etc.
1.2.1. Am I able to use it?
You are able to use this service on any sort of Internet connection that can connect to the update server at Geeks Anonymous. Your ISP, however, may not allow you to have people connecting to the IP address that the host name will resolve into. You should check with your ISP if you are allowed to run what they would term as servers or services. By using the dynamic DNS services to simply keep track of your IP, there should not be any issues with your ISP. If, however, you are running web services, FTP servers, or other such bandwidth intensive services, your ISP may not be pleased.
So, the simple answer is, yes. Anyone can use this service, according to the terms of service.
2. How it Works
In theory, the dynamic DNS system is setup so that a user anywhere can easily update a hostname that will resolve into their IP address. This means that instead of having to tell people to connect to, for example, 192.168.1.3, you can instead have them connect to myhost.dyn.geeksanon.ca. This is especially handy for people that have IPs that change frequently (such as some DHCP users, or dial-up users). Also keep in mind that all that we can offer you is something called forward resolution. What that means, is we can only provide a mapping of your desired hostname to your IP address. We cannot offer the reverse mapping, where when you connect to another site on the Internet, your IP address resolves into your hostname. That is far beyond our control. We would offer that if we could.
2.1. First Half of Services
The entire system is based around two things. First, there is the main web administration half. This is where you can connect to our servers using a web browser and update your configurations manually. By doing this, you have exact control over when your host gets updated, what IPs get set, and the other settings of the hostname.
2.2. Second Half of Services
The other half of the service uses custom programs that you run on your computer, and that we run on our servers. The client program connects periodically (at a period set by you) to the update server. This server then receives the information such as your IP address, username, and password. This information is verified and inserted into the database. This is all done automatically (or semi-automatically), allowing you to simply have the hostname updated as needed.
3. Server Side
On the server side of things, a few things are done with your information and your updates. The user account information that you provide when you create an account is stored in a database, along with all of your host records. When you update or add a host, the server will detect these changes within 5 seconds. When the changes are seen, it regenerates the host information for our name servers.
4. Recorded Information
A few pieces of information are set in the public DNS records. This includes your e-mail address, so be aware of that. This is more or less a simple way of users trying to find out who is hosting a service at that hostname (to ask questions, or whatever else). Your e-mail address will show up in two locations. First, in a TXT record. The other location is in the RP record. The TXT record is simply a free-form text field that is stored in a DNS server. This can be retrieved by various utilities, but is normally left alone. The RP (responsible person) record is set with an e-mail address and a domain name to check for more information. This is set to your e-mail and the domain you are being hosted under.
Once these are set and configured, they are all set to expire within 15 seconds of a client looking up your hostname. This lets changes to the name service be noticed rapidly across the entire Internet. This also means that if you update your IP address, the changes will take approximately 15 seconds before anything can see the new information.
4.1. MX Records
You will also find in the configuration section that you are able to set an MX record. This is a mail exchanger. What this accomplishes, is any e-mail sent to myhost.dyn.geeksanon.ca (for example), will be sent instead to the host defined in the MX record. The MX priority is only for those that know what they are doing. It can safely be left at the default value. If you have no idea what an MX record is for, or if you run a mail server, it is best to leave this value blank.
5. Conclusion
That's about all there is to know about this setup. It's not perfect, but it does work. If you have questions, you are welcome to contact the administration. We like questions. Also, contact the administration if you have any strange requests or would like your entire domain name hosted as a dynamic DNS service.