CDN Migration Checklist: 8 Key Things to Do Before Switching Providers

What is CDN Migration?

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CDN migration refers to the process of moving your website's content delivery services from one CDN provider to another. This involves transferring the responsibilities of storing, handling, and delivering your web content to a different network of servers.

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CDN migration is a critical step for businesses that rely on fast and efficient content delivery to their users. It encompasses not just the transfer of data and configurations but also involves a strategic re-evaluation of how your content is delivered globally. 

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Why Switch CDN Providers?

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Switching CDN providers is a decision that typically stems from the need to improve website performance, and cost-efficiency, or to avail of better features and support. As the digital landscape evolves, so do the demands on CDN services.

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A provider that was suitable a few years ago might not meet the current needs of a growing and dynamic website. Factors like increased traffic, expanding global reach, changes in content types, and the need for advanced security features can drive the decision to switch providers.

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Moreover, the rapid advancements in CDN technology mean that newer providers might offer more optimized and efficient ways to deliver content. They may provide better analytics, more robust security measures, or improved caching strategies, all of which contribute to a superior user experience. 

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In some cases, businesses might find that their current CDN is no longer cost-effective, prompting a switch to a provider that offers better value for money. Ultimately, the decision to change CDN providers should be driven by a strategic evaluation of how well your current CDN aligns with your evolving business objectives and technical requirements.

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CDN Migration Checklist for 2024

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Here is a complete CDN migration checklist for the year 2024, ensuring you a smooth transition:

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1. Preparation

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Objective: To gain a comprehensive understanding of your current CDN setup and anticipate potential challenges in the migration process.

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Action Steps:

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• Consolidated Review and Inventory Analysis: Begin by assessing your existing CDN’s performance. Look into metrics such as response times, cache hit rates, and data transfer volumes. Simultaneously, conduct an inventory of all active domains, SSL/TLS certificates, URL patterns, API endpoints, and special rules like URL redirects or rewrites. This dual approach helps in understanding both the performance and the structural aspects of your current CDN, which is essential for a smooth transition.
• Focused Configuration Assessment: Delve into your CDN’s existing configuration settings. Prioritize reviewing key elements like caching strategies (paying particular attention to TTL settings for different content types) and security configurations (including DDoS protection and Web Application Firewall rules). The aim here is to identify configurations that are critical for replication or optimization in the new CDN environment. This step ensures you don't overlook any configurations that are vital for maintaining performance and security standards.

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2. Proof of Concept

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Objective: Validate that the new CDN meets or exceeds current performance and security standards without unexpected costs.

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Action Steps:

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• Integrated Testing Environment Setup and Configuration Analysis: Develop a testing environment that closely mimics your live environment. Use this setup to route a limited amount of real traffic to the new CDN, providing a realistic assessment of its performance. In this environment, implement your current CDN’s configurations. Focus on identifying and testing potential optimizations unique to the new CDN, such as advanced compression algorithms or more efficient routing protocols.
• Success Criteria Establishment: Define clear, quantifiable objectives for the migration. These objectives might include improved load times, reduced bandwidth costs, or advanced security capabilities. This step is about setting measurable benchmarks to evaluate the new CDN’s performance against your current setup.

3. Implementation

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Objective: Ensure a seamless transition to the new CDN with minimal disruption.

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Action Steps:

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• Comprehensive Production Setup and Staging Validation: Configure the production environment of the new CDN, including the setup of SSL/TLS certificates and the final version of your CDN configurations based on the Proof of Concept results. Before going live, rigorously test this setup in a staging environment to catch any potential issues.
• Strategic A/B Testing and Service Changeover Planning: Implement A/B testing to direct a portion of your traffic to the new CDN. Compare key metrics against the old CDN to fine-tune performance. When ready, carefully update your DNS settings to point to the new CDN, ensuring you do so during low-traffic periods. Have a clear rollback plan in place for any unforeseen issues that might arise during this critical changeover phase

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4. Gradual Traffic Migration via DNS Configuration

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Objective: To facilitate a controlled and risk-minimized transition of traffic from the old CDN to the new CDN.

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Action Steps:

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• Initial Traffic Routing: Configure DNS settings to route a small portion of global or location-specific traffic through the new CDN while keeping the bulk of the traffic on the old CDN. This step ensures a controlled introduction to the new CDN without major disruptions.
• Performance Comparison: Continuously monitor and compare key performance metrics such as load times, error rates, offloading efficiency, and accuracy of returned headers between the old and new CDNs. This analysis is crucial for verifying that the new CDN correctly handles your traffic and meets performance expectations.
• Incremental Traffic Increase: Gradually increase the amount of traffic routed through the new CDN by adjusting DNS settings. Monitor each increment for stability and performance. This stepwise approach allows for early detection and resolution of issues.
• Extended Dual-Running Phase: After shifting the majority of the traffic to the new CDN (up to 99%), continue operating both CDNs in parallel for at least three months. This period is essential for enabling a potential rollback in case of issues and for comparing behaviors on both CDNs to identify if issues are related to the new CDN or independent of the CDN layer.

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5. Refined CDN Zone Setup and Content Handling

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Objective: To optimize the new CDN configuration for specific content delivery needs.

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Action Steps:

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• Zone Configuration: Set up and fine-tune CDN Zones in the new CDN, focusing on origin server specifications, cache expiration policies, and content handling rules.
• Content Type Optimization: Implement settings tailored to different content types within your CDN Zone, such as aggressive caching for static content and frequent updates for dynamic content.
• Feature Utilization: Explore and activate CDN-specific features like image optimization or mobile device detection to enhance the end-user experience.

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6. Asset Delivery Verification and Performance Assessment

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Objective: To ensure efficient asset delivery through the new CDN and evaluate performance improvements.

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Action Steps:

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• CDN URL Testing: Use various tools to test the accessibility of assets via the new CDN URLs and ensure correct HTTP response codes are returned.
• Performance Evaluation: Conduct a thorough analysis of load times, HTTP status codes, and other performance metrics to ensure there is no degradation in performance after switching to the new CDN.

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7. Complete Website and CDN Integration

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Objective: To fully integrate the new CDN into the website's infrastructure without issues.

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Action Steps:

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• Website Configuration Update: Adjust your website’s settings to direct asset requests to the new CDN, including changes in application configurations and HTML code as necessary.
• Plugin and Tool Configuration: For CMS-driven sites, update CDN-related plugins to the new CDN’s details, ensuring correct URL rewriting and feature utilization.
• Extensive Integration Testing: Perform detailed testing to confirm that all website assets are properly loading from the new CDN, with no broken links or load failures.

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8. Ongoing CDN Performance Monitoring and Management

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Objective: To continuously oversee the new CDN's performance and manage the migration process.

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Action Steps:

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• Performance Tracking: Regularly monitor key metrics using tools like Google Analytics and CDN-specific analytics to ensure optimal CDN performance.
• Log Review for Insights: Analyze CDN and server logs to understand traffic patterns and identify any security threats or performance bottlenecks.
• Real-User Smoke Testing: Conduct tests simulating user interactions to ensure website functionality and performance are maintained post-migration.
• Configuration Management and Documentation: Use configuration management tools to track changes in your CDN settings, which is vital for auditing and quick rollback if issues arise.

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Conclusion

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In conclusion, a successful CDN migration is a process that requires careful planning and execution across various technical and strategic dimensions. Proper preparation, testing, implementation, and ongoing management are required to leverage the full benefits of a new CDN provider, enhancing your website's performance, and aligning with your evolving digital strategy.

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