At its simplest, IPUpdate can be used to change the IP address for one or more domains. Starting with this premise IPUpdate can be used for a number of purposes. The most common purpose is to keep your domains current with your dynamic IP address. Other enterprising individuals can use IPUpdate to change the IP address for their domains to a backup IP if the main server goes offline. IPUpdate uses external getip agents to determine what IP address should be used for configured domains at any given time. This makes it trivial for system administrators to write custom scripts or programs that give ipupdate the IP address that should be assigned to configured domains. When daemonized, IPUpdate will check these getip agents every 5 minutes to see when an update is necessary. Or, you can schedule IPUpdate to run at different intervals using different service-specific configuration files.
The only requirement for IPUpdate to do its job is a dns server compatible with RFC 2136 dynamic update. This is a DNS protocol that enables clients to change dns information on the dns server remotely. DNS servers that support dynamic update include BIND, Simple DNS, and Microsoft DNS Server. When enabling your dns server to accept remote dynamic updates, security becomes a serious issue. As a solution, IPUpdate supports TSIG authentication, which is supported by BIND and SimpleDNS. Unfortunately, Microsoft DNS Server only supports GSS-TSIG, which is not supported by IPUpdate. IPUpdate can be used to send unsecured dynamic updates to Microsoft DNS Servers, but this isn't recommended.
IPUpdate is one of the few clients out there that supports dynamic update. The fact that it is free, open-source, and multi-platform capable makes it uniquely suited for your IP updating needs.