Dynamic Domain Name System (DDNS) is a method of automatically updating a name server in the Domain Name System (DNS), often in real time, with the active DNS configuration of its configured hostnames, addresses or other information.
The term is used to describe two different concepts. At the administration levels of the Internet, "dynamic DNS updating" refers to systems that are used to update traditional DNS records without manual editing. These mechanisms are explained in RFC 2136, and use the TSIG mechanism to provide security.
Another kind of dynamic DNS permits lightweight and immediate updates to its local database, often using a web-based mechanism. It is used to resolve a well-known domain name to an IP address that may change frequently. It provides a persistent addressing method for devices that change their location or configuration.
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LILIN offer a free DDNS service for use with LILIN equipment. A guide to configuring and using your free LILIN DDNS account can be found here