---
id: architecture
title: Architecture
sidebar_label: Architecture
---

![Architecture Diagram](/img/arch_no_grid.svg)

Four Cache Behaviours are created in CloudFront.

The first two `_next/*` and `static/*` forward the requests to S3.

The third is associated to a lambda function which is responsible for handling three types of requests.

1. Server side rendered page. Any page that defines `getInitialProps` or `getServerSideProps` method will be rendered at this level and the response is returned immediately to the user.

2. Statically optimised page. Requests to pages that were pre-compiled by next to HTML are forwarded to S3.

3. Public resources. Requests to root level resources like `/robots.txt`, `/favicon.ico`, `/manifest.json`, etc. These are forwarded to S3.

The reason why 2. and 3. have to go through Lambda@Edge first is because the routes don't conform to a pattern like `_next/*` or `static/*`. Also, one cache behaviour per route is a bad idea because CloudFront only allows [25 per distribution](https://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/cloudfront-limits.html#limits-web-distributions).

The fourth cache behaviour handles next API requests `api/*`