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Allowlist-Based Header Values

Allowlist-based header values help confirm the legitimacy of requests coming from the Prerendering service to your origin server, ensuring both security and integrity.

What Are Allowlist-Based Header Values?​

Allowlist-based header values are custom headers that act as a security mechanism during the prerendering process. They allow you to validate that incoming requests to your origin server are legitimate and are indeed coming from the Prerendering service.

Why Use Allowlist-Based Header Values?​

  • Security Measures: These header values are primarily used as a security measure to protect against potential threats like DDOS attacks by filtering out illegitimate requests.
  • Request Verification: They can contain customer-specific secret values, serving as a secure handshake between your system and the prerendering service.
  • Resource Allocation: Knowing that a request is valid allows your server to allocate resources more efficiently, ensuring a smoother prerendering process.

How Do Allowlist-Based Header Values Work?​

When a page is being prerendered—either on-demand or during prefetching—the Prerendering service attaches an allowlist-based header value to the request sent to your origin server. Your server, configured to recognize this header, validates the request before proceeding with the rendering process.