How did registering a domain for wanacry allow Marcus Hutchin prevent wanacry from causing any more trouble?

Question

How does it work?

Answer 1

Marcus Hutchins and Jamie Hankins, who were working from their homes in the U.K. for Los Angeles-based cybersecurity company Kryptos Logic, had just stopped a global cyberattack dead in its tracks. Hours earlier, WannaCry ransomware began to spread like wildfire, encrypting systems and crippling businesses and transport hubs across Europe. It was the first time in a decade a computer worm began attacking computers on a massive scale. The U.K.’s National Health Service (NHS) was one of the biggest organizations hit, forcing doctors to turn patients away and emergency rooms to close... By registering the domain, Hutchins had “sinkholed” the ransomware, allowing him to capture and dispose of malicious internet traffic. It was not unusual for Hutchins to find and register a domain found in a malware sample. As part of his botnet and malware tracking efforts he would often take control of unregistered domains — assuming they were a malware control server — to see how far and fast the malware was spreading. The end goal was to direct the malicious traffic into a void to identify victims and prevent further infections.

https://techcrunch.com/2019/07/08/the-wannacry-sinkhole/