Renting a high-defense CDN service is an important measure to protect website security and provide stable access. When choosing a high-defense CDN service, there are several key aspects to consider:

　　1. DDoS protection capabilities: Ensure that the high-defense CDN service provider has strong DDoS protection capabilities and can resist DDoS attacks of various types and sizes. Understand its protection technology, attack defense capabilities and experience, and confirm that it can effectively reduce the impact of attacks on your website.

　　2. Global coverage of edge nodes: High-defense CDN services should have global edge nodes to ensure that users can access your website nearby and provide stable acceleration effects. Understand the distribution of its edge nodes to ensure good acceleration effects in different regions.

　　3. Bandwidth and traffic limits: Verify the bandwidth and traffic limits of the high-defense CDN service to ensure that they meet your needs. Based on your website traffic and expected visits, choose appropriate bandwidth and traffic limits to ensure your website can function properly and withstand high traffic.

　　4. Cache strategy and cache control: Understand the cache strategy and cache control functions of high-defense CDN service providers. These features can help you optimize your website's performance and loading speed. Make sure the CDN can properly cache and update your website content to provide the best user experience.

　　5. Security and protection functions: High-defense CDN services should have effective security protection functions, including Web application firewall (WAF), attack logging and real-time monitoring. These features can help identify and block potentially malicious behavior and provide an extra layer of security to protect your website and user data.

　　Choosing a suitable high-defense CDN service requires comprehensive consideration of its DDoS protection capabilities, global edge node coverage, bandwidth and traffic restrictions, caching policies and controls, security protection functions, technical support and response time, as well as price and contract terms. Carefully evaluate these factors and choose a trustworthy high-defense CDN service provider that can effectively protect your website security and provide a good user experience.