Origin

Architecture

The server (or group of servers) that holds the authoritative version of your content. When a CDN cache miss occurs, the edge fetches from origin. Also called the origin server or backend.

Updated Mar 9, 2026

Full Explanation

The origin is where your content actually lives. Your application server, your object storage bucket, your CMS. The CDN sits in front of it, caching responses so the origin doesn't have to handle every request.

A well-configured CDN should handle 90%+ of traffic at the edge, with only cache misses and uncacheable requests reaching the origin. This is called origin offload. If your origin is getting hammered, either your cache hit ratio is low or you're not caching enough content.

Origin configuration matters. You want persistent connections between CDN and origin (avoid TCP handshake overhead on every miss), origin shields to consolidate misses, and health checks to detect failures before users do. Most CDNs let you configure multiple origins with failover rules.

Examples 

# CloudFront origin configuration (Terraform)
resource "aws_cloudfront_distribution" "cdn" {
  origin {
    domain_name = "api.example.com"
    origin_id   = "api"
    custom_origin_config {
      http_port              = 80
      https_port             = 443
      origin_protocol_policy = "https-only"
      origin_keepalive_timeout = 60
      origin_read_timeout      = 30
    }
  }
}

# Nginx: proxy to origin with keepalive
upstream origin {
    server 10.0.1.100:443;
    keepalive 64;
}
location / {
    proxy_pass https://origin;
    proxy_http_version 1.1;
    proxy_set_header Connection "";
}

Video Explanation

Frequently Asked Questions

The server (or group of servers) that holds the authoritative version of your content. When a CDN cache miss occurs, the edge fetches from origin. Also called the origin server or backend.

# CloudFront origin configuration (Terraform)
resource "aws_cloudfront_distribution" "cdn" {
  origin {
    domain_name = "api.example.com"
    origin_id   = "api"
    custom_origin_config {
      http_port              = 80
      https_port             = 443
      origin_protocol_policy = "https-only"
      origin_keepalive_timeout = 60
      origin_read_timeout      = 30
    }
  }
}

# Nginx: proxy to origin with keepalive
upstream origin {
    server 10.0.1.100:443;
    keepalive 64;
}
location / {
    proxy_pass https://origin;
    proxy_http_version 1.1;
    proxy_set_header Connection "";
}

Related CDN concepts include:

  • Edge Server — A CDN server located at the network edge, close to end users. Handles caching, SSL …
  • Origin Health Check — Periodic requests to a specific endpoint (usually /health or /ping) to verify the origin is …
  • Origin Shield — A mid-tier cache layer that sits between edge servers and the origin. Aggregates cache misses …
  • Cache Hit Ratio (CHR) — The percentage of requests served from cache versus total requests. A CHR of 95% means …
  • Failover — Automatically switching to a backup server, origin, or CDN when the primary one fails. Good …
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