Recital 28
Digital & dataLevel 1DirectiveePrivacyIn forceOfficial source
The obligation to erase traffic data or to make such data anonymous when it is no longer needed for the purpose of the transmission of a communication does not conflict with such procedures on the Internet as the caching in the domain name system of IP addresses or the caching of IP addresses to physical address bindings or the use of log-in information to control the right of access to networks or services.