Definition
A CDN distributes static resources (images, CSS, JS) and sometimes HTML across a worldwide network of edge servers. For SEO, the impact is multiple: TTFB and load time reduction (Core Web Vitals), better site availability (uptime), DDoS protection, and uniform performance regardless of visitor country. Modern CDNs like Cloudflare, Fastly, and AWS CloudFront also offer advanced SEO features: edge computing (Workers), automatic compression (Brotli), image optimization, HTTP/2-3, and intelligent caching. Key considerations include correct cache header configuration, canonical management with the CDN, and avoiding duplicate content between origin and CDN domains.
Key Points
- Significant TTFB reduction and Core Web Vitals improvement
- DDoS protection and improved site uptime
- Configure cache headers correctly to avoid stale content
Practical Examples
CDN for an international site
A site with visitors in 30 countries enables a CDN and sees average TTFB drop from 800ms to 120ms for distant visitors, improving LCP by 2 seconds.
CDN cache and fresh content
A news site configures short TTLs (5 minutes) for HTML and long TTLs (1 year) for static assets, balancing content freshness and performance.
Frequently Asked Questions
Indirectly, yes. Google uses Core Web Vitals as a ranking factor, and a CDN significantly improves TTFB and LCP. A faster site also offers better user experience, reducing bounce rate.
Cloudflare is the most popular (free plan available) with integrated SEO features. Fastly and AWS CloudFront are preferred for high-traffic sites. Choice depends on your budget, traffic, and edge computing needs.
Go Further with LemmiLink
Discover how LemmiLink can help you put these SEO concepts into practice.
Last updated: 2026-02-07