A Dynamic Update Client (DUC) is a program that redirects requests from a given URL to an IP address that is dynamically determined. Computer programs (also software programs, or just programs) are instructions for a Computer. Uniform Resource Locator is an URI which also specifies where the identified resource is available and the protocol for retrieving it An Internet Protocol ( IP) address is a numerical identification ( Logical address) that is assigned to devices participating in a Computer network This allows one to provide a fixed URL for an IP that changes. In some cases, the DNS host name of the IP will provide the same function.