Dynamic DNS (DDNS): What is it and How Does it Work?

Before the internet evolved into what it is today, IP (internet protocol) addresses seldom changed. But with the booming growth of web-based sites and services, static IP addresses have become increasingly harder to obtain. This predicament inspired the development of Dynamic Host Configuration Protocol (DHCP). DHCP allows internet service providers (ISPs) to dynamically assign IPs from a pool of addresses.

Tip: Want to learn more about how DNS works? Visit our What is DNS resource or our DNS Explained video.

What is Dynamic DNS

Dynamic DNS (DDNS) is a service that automatically checks for updated IP addresses for a website, server, or application. While DDNS is often associated with home use, it’s also implemented by businesses that provide services that don’t have static IPs. DDNS can be used for a variety of purposes, such as email, ftp, web, and game servers, or virtual private networks (VPNs), and security cameras.

How Does Dynamic DNS Work

Many DDNS services are implemented using provider-based software or a DHCP server that runs on a system. When changes are detected, the DDNS client passes along any necessary arguments for http or https URL requests to resolvers. When DDNS is configured, the software or DHCP server alerts all systems of any IP address changes for a domain or application. This ensures that updates to IPs are instantly propagated and that there is no interruption in service.  

Benefits of Dynamic DNS

Using Dynamic DNS is beneficial for applications and API calls that don’t (or can’t) use a static IP address but still need to be accessible for users at all times. Without a static IP, domains that point DNS records to a specific address could be unreachable for up to 24-48 hours before a change has propagated across all servers worldwide. As you can imagine, this would be problematic for businesses and end users. DDNS solves this problem as it essentially creates a dynamic A record. Rather than having to manually change an IP address every time it has been changed by an ISP, a DDNS service would do this automatically, while also avoiding any lag or downtime.

Like regular DNS, DDNS allows users to access IP addresses by a domain name. This way, anyone trying to access a particular service wouldn’t have to remember the numerical address. A good example of this would be an online security camera or DVR configuration. Without DDNS, you would need to type in the actual IP of the system you’re accessing. DDNS alleviates this problem. Another benefit to using DDNS is cost. As static IPs are harder to come by, they can be costly, especially for businesses that require large groups of them.

The Difference Between DNS and Dynamic DNS

Both DNS and DDNS translate domain names into numerical addresses that devices can read. The main difference is that standard DNS points to a static IP and requires manual updates. Dynamic DNS, on the other hand, uses dynamic IPs and continuously checks for IP changes and updates them automatically. For businesses, DDNS is handled by a standalone service, on an internal system, or through DNS providers that support dynamic DNS.

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Knowledge Base Article: https://support.dnsmadeeasy.com/support/solutions/articles/47001122450-dynamic-dns