dynamic DNS
also: DDNS, dynamic domain name system
A system that automatically updates DNS records when a computer's IP address changes, allowing services to remain accessible even though the IP is not static.
Dynamic DNS (DDNS) solves the problem of accessing a system whose IP address changes frequently. Without DDNS, you'd need to manually update DNS records every time your ISP assigns you a new IP address, making it impossible to maintain reliable access to services like a home server or website.
DDNS works by running a client that monitors your system's current IP address and automatically notifies a DNS server whenever it changes. The DNS server then updates its records so that your domain name continues to resolve to your correct IP. For example, if you run a web server at home with a dynamic IP from your ISP, a DDNS client can keep myserver.example.com pointing to whichever IP address you currently have.
Common DDNS services include DynDNS, No-IP, and Cloudflare. Most home routers have built-in DDNS support, or you can run a DDNS update client directly on Linux using tools like ddclient or inadyn.