To be honest, when I first saw these two terms, the image that came to mind was: single-machine defense means one machine handles the attack alone, while cluster defense means a bunch of machines handle it together. This understanding isn't entirely wrong, but in practice, the difference is huge. If you're choosing a Hong Kong DDoS protected server, or if your website is frequently under attack, understanding these two concepts can save you a lot of money.
First, understand one premise: Hong Kong is a special case. As a network hub in the Asia-Pacific region, Hong Kong's bandwidth resources are actually quite limited. Its international bandwidth exports are limited, and the available defense resources are also limited. In other words, renting a DDoS protected server in Hong Kong isn't like renting one in the US or Europe, where you can easily get hundreds of gigabytes or even terabytes of defense capability.
Therefore, Hong Kong's DDoS protected solutions naturally fall into two categories: single-machine defense and cluster defense. The logic behind these two approaches is completely different.
What is single-machine defense? In short:
Single-machine defense means your server handles all the attack traffic by itself.
Each individual server has a fixed defense limit, such as 50Gbps, 100Gbps, or 200Gbps. This value represents the maximum capacity your machine can handle.
This is similar to how everyone has a strength limit. If a person's strength is 100 jin (50 catties), and a 150 jin (75 catties) weight comes at them, they can't lift it alone.
The working principle of single-machine defense is as follows: The data center configures switches or routers to redirect attack traffic to the port where your machine is located. The cleaning equipment protects this port, dropping traffic or blocking the IP address if the threshold is exceeded. The entire process is "one-to-one"—the defense resources are bound to your machine.
What are the advantages of single-machine defense?
The first advantage is stability. The defense capability is exclusive and cannot be affected by others. If your neighbor's server is overwhelmed, it doesn't affect you. Your resources remain yours.
The second advantage is simple configuration. Basically, you can use it immediately after purchase, without complex scheduling and configuration. This is suitable for users who are not technically proficient or do not have dedicated personnel to maintain the high-defense system. The third advantage is low latency. Because the defense is completed locally, traffic doesn't need to be routed to other scrubbing centers, which is more suitable for businesses with high real-time requirements.
What are the pitfalls of single-machine defense?
The biggest pitfall is the fixed defense cap. If you buy 100G, you can only handle 100G. If the attack exceeds this limit, the service will be interrupted. And with limited bandwidth resources in Hong Kong, single-machine defense reaching 200G is already very expensive; increasing it further increases the cost exponentially.
Another pitfall is vulnerability to targeted attacks. Attackers only need to know your server's IP address to launch precise attacks. They can attack exactly what your defense value is. Some unscrupulous providers will even split the same physical machine into multiple virtual machines, but the defense value is still calculated based on the total bandwidth, resulting in each virtual machine actually providing far less defense than the advertised value.
What is cluster defense? It's completely different from single-machine defense.
The logic of cluster defense is entirely different. It's not a single machine fighting, but a pool of defense resources across an entire data center, or even multiple data centers, working together to provide protection.
To illustrate: single-machine defense is like someone holding a shield to block arrows; cluster defense is like an army behind you. Enemy arrows are partially blocked by the outer shield formation before reaching you.
The core of cluster defense is the concept of a "shared pool." A data center has an overall defense capacity limit, such as 500Gbps. This capacity isn't allocated to a single machine, but is shared by all users renting cluster defense services. When a machine is attacked, the entire data center's scrubbing equipment works in unison, redirecting attack traffic to the cluster's scrubbing center for processing.
More advanced cluster defense also supports cross-regional scheduling. If the Hong Kong data center can't handle the load, it can automatically redirect traffic to other overseas nodes for scrubbing, and then send it back.
What are the benefits of cluster defense?
The biggest benefit is elasticity. Defense capacity isn't fixed; it can dynamically expand based on the scale of the attack. If you encounter a 50G attack today, the cluster will use 50G of capacity to block it for you; if you encounter a 500G attack tomorrow, the cluster will allocate 500G of resources. This is impossible in single-machine defense mode.
The second advantage is cost-effectiveness. For the same 100G defense capability, cluster defense is usually much cheaper than single-machine defense because you are using it in a shared pool, not having exclusive access to a single resource.
The third advantage is strong resistance to large traffic volumes. Single-machine defense is capped at 200-300G, while cluster defense can handle 500G, 800G, or even terabytes. For businesses like video websites, games, and finance that are prone to attacks, this difference is crucial.
What are the pitfalls of cluster defense?
The biggest pitfall is "sharing." Since it's a shared pool, if multiple machines are attacked simultaneously, defense resources will be contested. First come, first served, and later attackers may not get enough resources. This situation, while uncommon, does exist.
Another pitfall is latency. Cluster defense typically requires redirecting traffic to a scrubbing center, adding an extra hop in the routing process and potentially increasing latency by several to tens of milliseconds. This impact needs to be considered for highly latency-sensitive applications (such as real-time audio/video and high-frequency trading).
There's also a hidden pitfall—many vendors advertise "500G cluster defense," which refers to the total defense capacity of the entire data center, not the capacity available to your single machine. If a machine next door is under attack and consuming 300G of scrubbing resources, your machine will only be allocated 200G. Sales won't proactively inform you of this unless you ask.
Real-world scenarios: When should you choose which approach?
Scenarios for choosing single-machine defense:
Your business traffic is stable, with a consistent number of users daily, without sudden spikes. Attack history has never exceeded 50G. The business is extremely sensitive to latency, tolerating even a 5ms increase. The budget is sufficient, and the extra cost isn't a concern. Examples include corporate websites, intranet systems, and small SaaS services.
Scenarios for choosing cluster defense:
Your business includes video websites, games, and e-commerce platforms. These industries are high-risk areas for DDoS attacks, characterized by high frequency and large scale. Your business traffic fluctuates, with fewer users during normal times and more during promotional events. You want to achieve high defense capabilities at a relatively reasonable cost. Examples include live streaming platforms, game servers, cross-border e-commerce, and financial transaction systems.
Another easily confused topic: DDoS protected servers vs. DDoS protected CDNs
Speaking of which, many people struggle when choosing a DDoS protection solution: should they use a DDoS protected server or a DDoS protected CDN?
Let's briefly differentiate them:
DDoS protected servers perform defense on the origin server side. Attacks directly hit your server, and regardless of its capacity, the server itself bears the pressure.
DDoS protected CDNs add a layer of nodes between the user and the origin server. When an attack comes, it hits the CDN node, not your origin server. As long as the node can withstand the attack, your origin server remains unaffected. Moreover, CDN nodes are distributed globally, making it impossible for attackers to locate your origin server.
So why use a DDoS protected server? Because CDNs are not suitable for all businesses. For scenarios like live streaming, gaming, and WebSocket long connections, CDNs struggle to cover the load. Furthermore, CDNs are billed based on traffic, so a surge in traffic during an attack can make the bill higher than the server cost.
The two aren't mutually exclusive; many companies use a combination of DDoS protected servers and DDoS protected CDNs. Under normal circumstances, the CDN handles the load; if the CDN can't keep up, the system switches back to the DDoS protected server. This solution is called "dual-layer protection," which is more expensive but offers significantly higher security.
Special Issues in the Hong Kong DDoS Protect Market: How to Avoid Pitfalls?
The Hong Kong DDoS protected market is quite complex, and I've seen many people fall into traps. Here are a few of the most common ones:
First, carefully check whether it's "dedicated" or "shared."
Some vendors offer very low prices, a few hundred dollars a month for 100G of DDoS protection. Upon inquiry, you'll find out this is the price for a "shared cluster." If the data center's total bandwidth is maxed out, your business will still be affected. True dedicated protection has independent resource verification, and the price won't be too low.
Second, clarify what happens during excessive attacks. If your DDoS protection is 100G and you receive a 150G attack, how will your service provider handle it? Some will simply block your IP address and unblock it once the attack stops. Others will offer temporary capacity expansion, but at an extra cost, which can be exorbitantly high. Make sure to clarify this before signing the contract.
Third, test the actual latency.
Network quality between Hong Kong and mainland China varies greatly. Some data centers boast impressive specifications, but in reality, peak packet loss exceeds 2%, making video playback unplayable. Before purchasing, it's best to ask the service provider for a test IP and run an MTR test to check the latency and packet loss to your primary users' locations.
Fourth, confirm your CC protection capabilities.
DDoS protection typically refers to Layer 4 attacks (SYN Flood, UDP Flood, etc.). However, CC attacks are Layer 7, and many servers claiming high protection don't actually protect against CC attacks, or their protection is very weak. If your business is vulnerable to CC attacks (e.g., websites, API interfaces), be sure to confirm whether your service provider has a WAF and a CC protection strategy. The choice between single-machine and cluster-based defense is essentially a trade-off between "determinism" and "elasticity." There's no absolute right or wrong, only what suits your needs. Before choosing, thoroughly understand your business situation—how much traffic do you have, how high is the attack risk, and how much loss would you suffer from business interruption—then compare it against the above criteria, and the answer will become clear.
