You’ve probably seen it in analytics dashboards, server logs, or privacy documentation: IP addresses with their last octet zeroed out. 192.168.1.42 becomes 192.168.1.0. For IPv6, maybe the last 64 or 80 bits are stripped. This practice is widespread, often promoted as “GDPR-compliant pseudonymization,” and implemented by major analytics platforms, log aggregation services, and web servers worldwide.

There’s just one problem: truncated IP addresses are still personal data under GDPR.

If you’re using IP address truncation thinking it makes data “anonymous” or “non-personal,” you’re creating a false sense of security. European data protection authorities, including the French CNIL, Italian Garante, and Austrian DPA, have repeatedly ruled that truncated IPs remain personal data, especially when combined with other information.

This is a fundamental misunderstanding of what constitutes effective anonymization. — Read More