What is a dynamic DNS and what is it for?

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Every day, we spend several hours browsing the internet and consuming information and services provided by the network, but have you ever wondered how domain names work or what dynamic DNS is? Understanding these concepts will help you better comprehend how we can access a remote site through an easy-to-remember name, even though it actually has an IP address associated with it. In this article, we will also explain how to configure a router with Dynamic DNS (DDNS).

Protocol and IP addresses

When we open our browser, the system sends a request to a remote server to establish a connection and share data. Initially, we do not know where the server comes from. This request is made through the communication protocol called TCP/IP.

This protocol, or rather, model, works on various layers of the network, from hardware-level access to the way information arrives on our desktop. In this article, we will focus on the layer 2 or Internet layer, where IP addresses come into play, which are necessary for any server or device on the network to “speak” on the network.

The IP address is a 32-bit or 4-byte number that uniquely identifies a host on the network and is separated into four parts by dots. Our computer, mobile phone or router has IP addresses, but the one that really interests us in this article is the router’s public IP address (the one that allows us to exist on the Internet). There are two types of public IP addresses:

Static IP: it is an IP address that is always the same, as it is associated with a particular machine and remains constant. This type of IP address is used in servers, as it is more convenient for administration to always have the same address and a DNS constantly pointing to it.

Dynamic IP: it is the IP address that our home routers normally have, as they are supplied through the ISP and can change each time the router starts.

What is the DDNS or Dynamic DNS and what is it for?

We know that each machine has an IP address, but there is also a name associated with internet services and hosts within an intranet, called a domain. The DNS (Domain Name System) is the mechanism responsible for translating this domain to the actual IP address with which we want to establish the connection.

For this transaction to take place, our equipment must have a DNS, which by default will be configured on our router to connect to a DNS database. However, we can modify this parameter in the operating system to assign a specific one, such as Google’s 8.8.8.8.

However, traditional DNS may have trouble resolving domain names whose associated IP address has changed, causing the host to be inaccessible during the time it takes for the changes to propagate on the server.

To solve this problem, Dynamic DNS (DDNS), DynDNS, or Dynamic Domain Name System, was created. This system associates the domain name with a dynamic IP address, so it is always up-to-date and accessible. The device connected to the DDNS service will inform it of its current IP address, which will keep the domain resolution active at all times.

What is the purpose of Dynamic DNS and what benefits does it offer?

Although major Internet providers and services have their own worldwide databases, Dynamic DNS can be very useful for individual users, small businesses, and even network administrators. In fact, a DynDNS can be used for several things:

Accessing our PC remotely from anywhere without needing to know its IP address
Allowing administrators to access local or remote servers
Setting up a multimedia server, mail server, FPS, or Samba at home
Connecting to a particular surveillance camera system from a mobile device

You may be wondering if it wouldn’t be easier to have a static public IP address and skip this step. Well, call your Internet provider, who will probably charge you an extra fee for providing this service, and you will still need a DNS to avoid having to constantly enter and filter your IP address.

So these are the advantages of a Dynamic DNS service:

Avoiding the need to use and filter the public IP address
Being able to assign any name we want to our host (as long as certain guidelines are followed)
Easily configuring it on the router
Being a free service for personal use, although companies have premium packages with more services
Avoiding the need to contract a static IP address service for the connection
Being able to integrate it with a VPN service, adding an extra layer of encryption and anonymity.

It’s also important to keep in mind the following:

If we want to access our computer remotely, we need to do additional work, such as opening ports or using uPnP when necessary.
Free services may have conditions such as domain extension, advertising, and certain limitations.
There may be cases where a router or device is not compatible with a particular service.
The domain name will never be owned by us.

How to configure Dynamic DNS on our router

Now that we know what Dynamic DNS is, let’s take an example of how to configure it on a home router from Asus, where the process is straightforward. During the process, we may encounter a problem that is not common, but it can serve as an example of what to do if it happens to you.

First, we need to access our router. To do this, we need to know the internal IP address of the router, enter it into a browser, and log in with the username and password. If we don’t know the IP address, we can open a command prompt (CMD) in Windows and type:

Ipconfig

Next, we go to the WAN section, in our case, and there we will find the DDNS option. The location of this option is almost the same in all routers. If it’s not there, we need to navigate through different sections to find it.

Here, a problem arises due to the particular conditions of this network: the router reports that it’s using a private WAN IP address. What does this mean? It means that the router is inside an internal network, in a NAT environment, and therefore its IP address doesn’t go directly to the internet but goes through a server that’s above it. It’s the same as a PC on our local network, it has a private IP address that we can’t access from outside.

As we mentioned, this is an uncommon case, but if it happens, we need to contact our internet provider to assign us our own public IP address that allows us to go to the internet without being inside their NAT. They probably offer a service to do this, but it would have an additional cost on the bill.

If this is not your case, you can proceed normally by selecting the “Yes, I want to enable DDNS client” option. In the Asus router, you can select several external DDNS services in addition to their own service Asus.com. To be more generic, we will select No-IP, one of the best-known ones.

Next, go to the No-IP website and register as a user on the platform. Once you have logged in, you will have access to a user panel where you can create your Dynamic DNS. Click on “Used Hostnames.”

In the new section, enter the domain you want to create, choosing one of the extensions offered by No-IP (obviously, they will not be .com or .es like the own domains). Usually, we will keep the first option in terms of the type of record, although it also supports IPv6. Immediately, you will see the public IP address to which the DDNS will point.

We go back to our router and log in with our username and password to the service. As soon as authentication is performed, the Dynamic DNS will be enabled and will point to our router.

If we go to the No-IP panel, we will see how the IP address to which our domain points appear next to it. Here we can see that our router has an internal IP address because it belongs to a NAT, so the service will not work for us. In your case, everything should work normally.

Now all that’s left is to configure the server we want on our computer, open ports if necessary, and assign a fixed internal IP address to the device we want to access. This is customary in these cases.

Conclusion about Dynamic DNS

In conclusion, Dynamic DNS is a widely used solution to take advantage of the services we can set up on a computer within our network, such as a media server or a remote desktop. Without DNS, we would have to access any internet service through an IP address, which would be a mess for the general public.

We hope that the explanation has been clear and that the example has served not only to configure your own DDNS, but also to see what particular problems you may encounter if you do not have a “typical” connection.