In 2023, the peak traffic of global DDoS attacks exceeded 3.47 Tbps, and in 2024, data from the China Academy of Information and Communications Technology (AICT) showed that 60% SMEs suffered more than 12 hours of business interruption due to cyber attacks. In the face of increasingly rampant cyber threats, how can enterprises choose between high defence servers and CDN defence? High-defence servers and CDN defence, where are the differences? Today, 08Host will bring you together to analyse the differences between the two from the technical principles, defensive capabilities, cost-effectiveness and other six dimensions.
I. "Genetic differences" between the two technologies
1. high defence server
High Defence Server (Anti-DDoS Server)It is a solution that intercepts malicious traffic at the entrance of a single server or server room through hardware firewalls, traffic cleaning centres and other technologies. Its core principle is shown in Figure 1:
- flow cleaning: Filter anomalous traffic (e.g. SYN Flood, UDP reflection attacks) by analysing packet characteristics.
- Bandwidth reserve: Usually equipped with bandwidth redundancy of 1 Tbps or more to cope with bursty traffic attacks.
- IP blacklisting: Update the attack source database in real time and automatically block malicious IPs.
2. CDN Defence
The Content Delivery Network (CDN) achieves attack decentralisation through globally distributed edge nodes. Its defence mechanism is shown in Figure 2:
- Node load balancing: Assigns user requests to the nearest node, hiding the source IP.
- edge cache: Static content is cached at the node, reducing the risk of exposure to back-origin requests.
- Web Application Firewall (WAF): Filtering application layer attacks such as SQL injection and XSS at the node level.
II. Comparison of defence capabilities
1. Anti-DDoS attack capability
| norm | high defence server | CDN Defence |
|---|---|---|
| Network Layer Attack Defence | Support SYN Flood, UDP Flood, etc. | Dependent on bandwidth reserves, weak to fragmentation attacks |
| Application Layer Attack Defence | Additional WAF deployment required | Integrated WAF to block HTTP/HTTPS attacks |
| Maximum defence bandwidth | Single node up to several Tbps | Dependent on the total number of nodes, the theory scales infinitely |
| typical case | GitHub suffered a 1.35 Tbps Memcached attack in 2018, which was defused by a high security cleaning centre. | Cloudflare successfully defended against the world's largest HTTP/2 DDoS attack in 2022. |
2. CC attack defence mechanism
- high defence server: Intercepted by threshold settings (e.g., single IP request frequency), but difficult to identify slow CC attacks.
- CDN Defence: Leveraging behavioural analytics + CAPTCHA challenges, such as Akamai's Prolexic solution to identify anomalous session patterns.
III. Comparison of speed and safety capabilities
1. Latency Comparison
- high defence server: The flow needs to go through the cleaning centre, which may add 10-50ms delay.
- CDN Defence: Edge node acceleration enables static content to load 30%-70% faster.
2. Applicable Scenarios
- high defence server:: Suitable for real-time interactive business (e.g., online gaming, financial transactions)
- CDN Defence: More suitable for content distribution businesses (e.g. e-commerce, video sites)
IV. Comparison of business costs
1. High Defence Server Cost Model
- Base cost: $800-$10000/month (based on bandwidth and defence thresholds)
- Excess traffic: billed at $0.5-2/GB after exceeding the threshold value
2. CDN Defence Cost Model
- Billing by request volume: $0.01-0.1/10,000 HTTPS requests
- Bandwidth cost: $0.1-0.5/GB
Case measurementsFor a video website with 1 million daily activities, choosing CDN defence can save about 40% cost (assuming an average daily bandwidth of 1 TB) compared with a high-defence server.
V. Deployment complexity comparison
1. Deployment steps for high defence servers
- Purchase high defence IP and bind the source site
- Configure protection policies (e.g. TCP/UDP protocol whitelisting)
- Setting up back-origin rules (requires modification of DNS resolution)
2. CDN Defence Deployment Steps
- Access to CDN service providers
- Configuring CNAME Resolution
- Setting cache rules and security policies
Operation and Maintenance Difficulties: High-defence servers require manual adjustment of protection thresholds, and CDN defence may face cache coherence issues.
Conclusion: there is no best option, only the most suitable scenario
| Selection of dimensions | Give priority to high defence servers | Preferred CDN defence |
|---|---|---|
| Type of attack | High Traffic Network Layer DDoS | CC attacks, application layer attacks |
| Nature of business | Real-time interaction, long connections | Content distribution, short connections |
| Budgetary constraints | Able to withstand high fixed costs | Want to pay on demand |
final recommendationFor super-large enterprises, "high defence server + CDN" can be used as a layered defence, while small and medium-sized enterprises can choose a single solution according to their business characteristics.