Content Delivery Network (CDN) is a service that provides content distribution and security to help protect websites from a variety of cyber attacks and malicious traffic. Here are some ways that high defense CDNS can defend websites:

1. Distributed cache: High-defense CDN will deploy server nodes around the world to cache the static resources of the website to these nodes. This allows users to access content from servers closer to them, reducing latency and network congestion.

2. DDoS attack defense: High-defense CDNS can defend against distributed denial of service (DDoS) attacks and disperse malicious traffic through traffic filtering and distribution. It can detect abnormal traffic patterns and isolate attack traffic, ensuring that normal users' access is not affected.

3. Web Application Firewall (WAF) : High-defense CDNS usually integrate the WAF function to detect and block malicious Web requests, such as SQL injection, cross-site scripting (XSS) attacks. Wafs can help protect web applications from common vulnerabilities.

4. SSL encryption: High-security CDN can provide SSL certificates to realize encrypted data transmission and protect the security and privacy of user data.

5. Hot link protection: High-security CDN can prevent other websites from directly linking to your resources without authorization, consuming your bandwidth and resources.

6. Cache control: With the cache control policy, you can set what content needs to be cached and what does not. This helps ensure that dynamic content is updated in a timely manner while reducing the burden on the server.

7. Dynamic content acceleration: High-defense CDN not only caches static resources, but also optimizes and accelerates dynamic content to provide a better user experience.

8. Security reporting and monitoring: High-security CDN usually provides real-time security reporting and monitoring to help you understand the security status of the website and detect abnormal activities in time.

9. Custom rules: High defense CDN usually allows you to customize defense rules and formulate security policies according to the specific needs of the website.

In summary, high-defense CDN provides comprehensive security protection for websites through distributed cache, DDoS defense, WAF, SSL encryption and other technologies. Choosing a high-security CDN provider that suits your website's needs and developing an appropriate security policy based on the features it offers can significantly improve the security and performance of your website.