Truncating the last octet of an IP address because it is not needed is an example of the privacy principle of Data Minimization. This principle states that only the minimum amount of personal data necessary for the purpose should be collected and processed. By truncating the IP address, the data is reduced to the minimum needed, thus limiting the potential for privacy breaches and data misuse. (Reference: IAPP CIPT Study Guide, Chapter on Data Minimization and Retention)