China has been hit by the \"largest ever\" attack on its Internet structure, crashing the country\'s .cn servers, according to a government-linked agency. The national domain name resolution service came under a distributed denial of service (DDoS) attack for around two hours early on Sunday, the China Internet Network Information Centre (CNNIC) said in a statement. Domain name resolution is a key part of how the Internet works, converting a website name into a set of digits -- the IP address -- that computers can recognise. The service in China focuses on websites with the .cn extension. DDoS attacks are attempts to overload a server with a huge number of requests, so that it interrupts or suspends its functions. A second wave of the assault in China two hours later grew into \"the biggest of its kind ever\", CNNIC said, without giving any indication of who might have been responsible. \"The resolution of some websites was affected, leading visits to become slow or interrupted.\" Washington has repeatedly accused China of waging hacking attacks on the websites of US government agencies and businesses. But Beijing has denied the accusations, saying China itself is a victim of Internet attacks