DynDNS

Dynamic DNS (DynDNS) is a service that automatically updates a domain name with the changing numeric address of a device on the Internet. It allows devices on networks with dynamic public IP addresses to remain reachable under a fixed domain name, avoiding manual DNS updates.

How it works: A dynamic DNS client runs on a computer, router, or dedicated device. It detects changes to the public IP address and sends an update request to the dynamic DNS provider, using authentication to verify the update. The provider then updates the DNS A (and sometimes AAAA) records for the designated domain or subdomain. The changes propagate through the DNS system, often with a short time-to-live to speed reachability after an update.

Use cases include remote access to home servers, CCTV or surveillance systems, gaming servers, or VPN endpoints. Dynamic DNS reduces the need to track and publish new IP addresses whenever the ISP assigns a new one.

Providers and availability: Numerous services exist, including the original DynDNS and other providers such as No-IP. Some services are free with limitations, while paid plans offer additional features and reliability. Many consumer routers include built-in DDNS clients, enabling automatic updates without separate software. Users should secure update credentials to prevent unauthorized changes, and be aware that some providers restrict updates to particular domains or IP ranges.

History and context: DynDNS became widely known as a practical solution for devices behind dynamic IP addresses. The DynDNS brand was associated with Dyn, a DNS services company that was acquired by Oracle in 2016 and integrated into Oracle Dyn.