What is IPv6? Unveiling the core technology behind China's network protection upgrade

When it comes to internet security, many people worry about one question: Can the United States really cut off China’s internet through root servers? This question conceals deeper concerns about cyber sovereignty. To understand the answer, we first need to grasp what IPv6 is and how it is rewriting the global internet landscape. IPv6 is not just a technological upgrade; it is a key to breaking the U.S. internet monopoly.

Why Upgrade from IPv4 to IPv6?

The internet was originally developed by the United States, and early network protocols were naturally set by Americans. Root servers are called the “central nervous system” of the internet, and their status is indeed special—there are only 13 root servers based on the IPv4 protocol worldwide, with one main root server in the U.S., and among the 12 secondary root servers, 8 are in the U.S., 2 in Europe, 1 in Japan, and 1 in South Korea. This setup is a result of historical factors, which inevitably causes concern.

However, the root of these worries lies in dependence on outdated technology systems. IPv4 is an early internet communication protocol with limited address space, and its architecture did not consider globalization needs. As internet users surged, IPv4’s limitations became apparent. IPv6 is the next-generation network protocol, offering almost unlimited address space and incorporating modern requirements such as security and optimization from its design inception.

The role of root servers in this system is not as mysterious as many think. They are like the “telephone directory” of the internet. When you enter a URL in your browser, you must first consult the root server to find the corresponding IP address before opening the webpage. But root servers only direct traffic—telling you, for example, that to query an address in Beijing, you should contact the 010 query server—the specific number is then looked up by lower-level servers.

Can Root Servers Really Cut Off a Country’s Internet?

Historically, there have been cases where the U.S. used control over root servers to exert political pressure. During the 2003 Iraq War, the U.S. shut down Iraq’s domain name resolution, causing the entire country to “disappear” from the internet. Libya also experienced a three-day blackout in 2004. These incidents indeed raised global concerns.

But these are stories from over a decade ago. If the U.S. could still freely control China’s internet access today, they would have already used this as leverage in negotiations—there’s no need to wait until now to discuss it. In fact, China has long recognized the seriousness of this issue.

As early as 2003-2004, Chinese decision-makers saw the potential risks of root server monopoly. They adopted a clever strategy—directly copying root server data and establishing mirror servers. In simple terms, mirror servers are like having a complete “telephone directory” copy stored locally. When browsing the internet domestically, users don’t need to go to the U.S. for queries; they can directly access local mirror servers for domain resolution.

By May 2025, only China Telecom’s research institute has deployed three root mirror servers in Guangzhou, Wuhan, and Zhengzhou. Coupled with years of prior deployment, China now has 10 root mirror servers within its borders. These mirror servers are synchronized in real-time with the original root servers. Even if the U.S. root servers become unresponsive, China’s own mirrors can handle the load, and with faster resolution speeds—since the data is right at home.

How China’s Mirror Servers and the Snowman Plan Break the Deadlock

A more critical change comes from technological generations. The era of IPv4 dominance is over; the world is undergoing large-scale IPv6 upgrades, which is akin to a reshuffle of the internet landscape.

The “Snowman Plan,” launched in 2016, marked the beginning of this technological revolution. It established 25 IPv6 root servers across 16 countries worldwide, with China hosting 4—1 main root and 3 secondary roots. This means China is no longer just relying on mirrors but has its own root servers.

Although these servers may seem small in number, they have broken the U.S. monopoly over root servers. The current global setup is 13 old root servers plus 25 new ones; the era of a single dominant country like the U.S. is gone forever.

China’s IPv6 development is also rapid. By September 2025, China had 865 million active IPv6 users, accounting for 77.02% of all internet users. This is a 294-fold increase from 2.93 million users in 2017. With such scale, even if the old IPv4 root servers face issues, the vast number of IPv6 users can still access the internet normally.

Domestic Innovation: From Red Maple System to Autonomous Root Domain Name Resolution

China’s network security is not just passive defense but actively building a fully autonomous technological system.

The Domain Name Engineering Center spent eight years developing a system called “Red Maple,” a fully自主 developed domain name software. Paired with domestically developed servers by Sugon, China has achieved successful deployment on domestically produced chips. These high-performance servers operate at 1.6 times the speed of international peers and can defend against 10G bandwidth attacks on a single server. Even if the U.S. attempts a DDoS attack to disable China’s domain system, it would be impossible.

More importantly, China led the drafting of the Internet security standard RFC8416 under IETF, establishing it as an international standard. This signifies China’s voice in cybersecurity, moving beyond passive compliance with U.S.-set rules.

Some point out that the U.S. blocked 36 Iranian .com domains in 2021, which did impact Iranian websites. But this is entirely different from outright disconnection. Iranian sites can switch to their own .ir domains to restore access; international access is affected but not completely cut off. China has long been aware of this potential risk. Although many domestic companies use .com domains, China’s top-level domain .cn is fully managed by China itself, overseen by the China Internet Network Information Center. The U.S. cannot arbitrarily interfere.

Why the U.S. Can No Longer Easily Control the Global Internet

Even in the most extreme scenarios, China has complete backup options. If necessary, they can switch services to the .cn domain, which would not affect domestic access. International access can be maintained through IPv6 root servers and mirror servers. This would not cause a total internet blackout like in Iraq.

Legally and practically, the U.S. can no longer easily take action against China. Although ICANN was once under U.S. Commerce Department control, it has gradually transitioned to international management. While the U.S. still has influence, it can no longer unilaterally decide everything as before.

China’s cyber sovereignty is now backed by clear legal protections. China has built its own autonomous root domain name resolution system, with domestic recursive servers directly pointing to its own root servers. Even if connection to international root servers is severed, the local network can still operate normally. Core functions like office systems, payment systems, and communication systems remain unaffected. It’s like a household telephone system—if international calls are blocked, local calls still work smoothly.

Currently, there are over 1,000 root mirror servers worldwide, with China’s deployment becoming increasingly dense. Coupled with IPv6 advantages,自主开发的红楓系统, domestically produced hardware and software, and the large-scale migration from IPv4 to IPv6, the idea that the U.S. can cut off China’s internet through root servers is completely unrealistic.

Therefore, those promoting the “internet shutdown crisis” are either misunderstanding the technology or trying to create panic for attention. A careful review reveals that China’s cybersecurity defenses are already quite solid. The legacy IPv4 setup was indeed a concern, but we are no longer in an era where 13 root servers can control the entire world.