Cloudflare has become an essential tool for major websites worldwide—but a recent outage on November 18, 2025, demonstrated its vulnerabilities. Millions of users experienced temporary disruptions on some of the biggest social media and online platforms, sparking renewed interest in understanding what Cloudflare is, how it works, and why it is so widely used.
What is Cloudflare and Why Do Websites Use It?
At its core, Cloudflare is a content delivery network (CDN) and internet security service designed to optimize website performance and protect against online threats. Normally, when a visitor accesses a website, they connect directly to the web server hosting the site. By integrating Cloudflare, traffic is routed through Cloudflare’s network first. This intermediary checks incoming requests, blocking malicious activity while allowing legitimate users to proceed.
The three main reasons sites adopt Cloudflare are:
- Free SSL and Basic Protection: Even the free plan includes SSL certificates, which encrypt traffic between visitors and the website.
- Global Speed Optimization: Cloudflare’s CDN caches content at multiple locations worldwide, delivering it faster to users regardless of geographic location.
- DDoS and Security Protection: Cloudflare acts as a shield against distributed denial-of-service attacks and other threats.
In short, it is a cost-effective solution that combines performance optimization with strong security measures. However, as November 18th showed, reliance on a single service provider can introduce a single point of failure risk.
How Cloudflare Works
Imagine a nightclub with a bouncer at the door. The bouncer (Cloudflare) checks IDs and decides who can enter. Inside, the DJ and bartender continue working (the website servers are operational), but no one can get in if the bouncer malfunctions. That is essentially what happened during the outage—Cloudflare’s network faced internal issues, preventing users from accessing websites despite servers being fine.
This illustrates the trade-off: while Cloudflare protects against external risks like cyberattacks, it also centralizes internet traffic, meaning problems on Cloudflare’s side can impact millions of websites simultaneously.
Technical Insights: Cloudflare’s Key Features
Cloudflare provides a wide array of services beyond basic DDoS protection, including:
1. DNS and Proxy Management
Cloudflare requires websites to route DNS through its network. Merely activating the “proxied” status for one DNS record is insufficient. Attackers can still discover unprotected subdomains through historical DNS records or external services like SecurityTrails, bypassing Cloudflare entirely. Best practices include:
- Ensuring all DNS records for the site are proxied.
- Using a new IP address if previous DNS records exposed the server.
- Restricting server ports (e.g., 80 and 443) to only accept connections from Cloudflare’s IP ranges.
2. Email and MX Records
Emails sent from your server may reveal its IP address. Using services like SendGrid or Office 365 can mask server origins. MX records, which route email, cannot be proxied, so consider third-party email solutions to avoid exposing your infrastructure.
3. Cloudflare Workers and Tunnels
Workers allow developers to run code on Cloudflare’s edge servers without hosting it themselves. Coupled with Cloudflare Tunnels, this enables secure access to internal services without exposing IP addresses or open ports—ideal for zero-trust networks.
4. Security: WAF, Rate Limiting, and Bot Management
- WAF (Web Application Firewall): Protects against SQL injection, cross-site scripting, and other attacks. Paid plans offer extended rulesets and bot protection.
- Rate Limiting: Prevents abusive requests from overwhelming servers.
- Zero Trust / Access Control: Restrict subdomain access to authorized users using identity providers like Azure AD or Google Workspace.
5. SSL Certificates
Cloudflare provides free SSL certificates for every website. Options include:
- Flexible SSL: Encrypts traffic from user to Cloudflare, but not Cloudflare to server.
- Full SSL: Encrypts traffic end-to-end, including server connection.
- Origin Certificates: Free, server-installed certificates valid only through Cloudflare.
6. Caching and Performance Optimization
Cloudflare caches static assets (images, CSS, JS) on edge servers, reducing bandwidth usage and improving load times. Advanced features like Argo Routing optimize traffic paths, reducing latency by up to 30%.
7. Load Balancing and Health Checks
For high-traffic sites, Cloudflare offers load balancing across multiple cloud providers, enhancing uptime and resilience. Health checks monitor server availability, and notifications alert administrators to downtime.
8. Turnstile: CAPTCHA Alternative
Cloudflare Turnstile serves as a privacy-focused alternative to reCAPTCHA, easily integrated with minimal code changes.
9. R2 Storage: S3-Compatible Object Storage
Cloudflare R2 provides cloud storage with CDN integration at competitive pricing. Compatible with most S3 APIs, it allows easy migration or dual-use setups.
10. Real-World Worker Use Case
For websites with seasonal spikes, developers can use Workers with D1 databases and cron jobs to handle API requests and synchronize with other backends. This eliminates the need to manage scaling manually, while leveraging Cloudflare’s edge computing infrastructure for performance and reliability.
Why Major Websites Trust Cloudflare
Despite occasional outages, Cloudflare remains widely used due to its ability to combine speed, security, and global scalability in a single platform. Its free tier provides entry-level protection for smaller websites, while enterprise plans offer advanced DDoS mitigation, WAF rules, traffic optimization, and zero-trust access.
The November 18 outage serves as a reminder that centralizing critical internet infrastructure has risks, but for most organizations, Cloudflare’s benefits in mitigating distributed attacks, speeding content delivery, and simplifying management outweigh the downsides.
