The Internet Corporation for Assigned Names and Numbers (ICANN), the organisation responsible for managing the DNS root zone, commissioned TNO to conduct research into the scalability of the root zone. What is the potential impact of the introduction of secure DNS (DNSSEC) and IPv6, and of the addition of Internationalised Domain Names (IDN) and new generic Top Level Domains (gTLDs), on the scalability and stability of the root zone, and hence the Internet itself? Could these developments cause the Internet to go ‘dark’ for the first time in its history? The DNS Root Scaling model developed by TNO can be used to quantitatively assess – and therefore prioritise – these risks. Partly on the basis of the initial results, ICANN was advised to temporise and monitor the developments already initiated.