DDNs

Dynamic DNS (DDNS) is a service that automatically updates a domain name’s DNS records to reflect changes in the IP address of a device. This allows a host with a dynamic or changing public IP to be reached by a constant domain name rather than by a changing IP.

How it works: A DDNS client runs on a device such as a router or computer. It monitors the device’s public IP address, and when a change is detected, it authenticates with a DDNS provider and issues an update request. The provider updates the domain’s A (and sometimes AAAA) records on their DNS servers, after which the domain resolves to the new IP. Updates are typically transmitted over HTTP or HTTPS using tokens or credentials. Some providers also support updates via RFC 2136 DNS dynamic updates or other protocols.

Typical use cases include remote access to home networks, hosting a small web server or CCTV/NVR system from a residence, running a game server, or accessing cloud-enabled IoT devices. DDNS is commonly used when a fixed public IP address is not available or is cost-prohibitive.

Components and options: A dynamic DNS provider, a registered domain or subdomain, and an update client (built into many routers or available as software on a PC or NAS). Many consumer routers offer built-in DDNS clients supporting providers like DynDNS, No-IP, or Duck DNS.

Limitations and security: DDNS relies on credentials and trusted DNS propagation; misconfiguration or credential compromise can expose the home network’s address. Providers may impose update limits and propagation delays. Security practices include using HTTPS, strong tokens, and IP allowlists. Alternatives include acquiring a static IP, using a VPN, or employing a reverse proxy with port forwarding.