Edge locations and CloudFront overview in AWS - Step-by-Step Execution

Process Flow - Edge locations and CloudFront overview

User requests content

↓

Request sent to nearest Edge Location

↓

Edge Location checks cache

↓

Serve cached

↓

Content delivered to User

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Edge caches content for future requests

User requests go to the closest edge location. If content is cached there, it is served immediately. Otherwise, the edge fetches from the origin, delivers it, and caches it for next time.

Execution Sample

AWS

User -> Edge Location -> Cache? -> Serve or Fetch -> Deliver -> Cache

Shows the path of a user request through CloudFront edge locations and caching behavior.

Process Table

Step	Action	Cache Check	Result	Content Source	User Delivery
1	User requests content	N/A	N/A	N/A	Waiting
2	Request reaches nearest edge location	Check cache	Cache miss	Origin server	Waiting
3	Edge fetches content from origin	N/A	Content retrieved	Origin server	Waiting
4	Edge delivers content to user	N/A	Delivered	Edge cache	Delivered
5	Edge caches content	N/A	Cached for future	Edge cache	N/A
6	User requests same content again	Check cache	Cache hit	Edge cache	Delivered
7	Edge delivers cached content	N/A	Delivered	Edge cache	Delivered

💡 Content is delivered either from cache or origin; subsequent requests use cached content until expiration.

Status Tracker

Variable	Start	After Step 2	After Step 3	After Step 5	After Step 7
Cache Status	Empty	Miss	Miss	Cached	Hit
Content Location	Origin	Origin	Origin	Edge cache	Edge cache
User Delivery Status	Waiting	Waiting	Waiting	Delivered	Delivered

Key Moments - 3 Insights

Why does the edge location fetch content from the origin server?

Because the cache check at step 2 shows a cache miss, so the edge must get the content from the origin (see execution_table row 2).

What happens when the user requests the same content again?

At step 6, the cache check results in a cache hit, so the edge serves the cached content directly without contacting the origin (see execution_table row 6).

Does the user always get content from the origin server?

No, only on the first request or cache miss. Later requests get content from the edge cache (see execution_table rows 4 and 7).

Visual Quiz - 3 Questions

Look at the execution table, what is the cache status after step 5?

A Cache is empty

B Cached

C Cache miss

D Cache hit

💡 Hint

Check the 'Cache Status' variable after step 5 in variable_tracker.

At which step does the edge location deliver content to the user for the first time?

A Step 4

B Step 3

C Step 6

D Step 7

💡 Hint

Look at the 'User Delivery' column in execution_table for when content is first marked 'Delivered'.

If the cache never stored content, how would step 6 change?

A User would not receive content

B Content would be delivered from edge cache

C Cache hit would become cache miss

D Origin server would be bypassed

💡 Hint

Refer to execution_table row 6 and variable_tracker for cache status changes.

Concept Snapshot

CloudFront uses edge locations to deliver content quickly.
User requests go to the nearest edge location.
If content is cached, it is served immediately.
If not cached, edge fetches from origin and caches it.
Subsequent requests use cached content until expiration.

Full Transcript

When a user requests content, the request goes to the nearest CloudFront edge location. The edge checks if it has the content cached. If yes, it serves the cached content immediately, making delivery fast. If not, the edge fetches the content from the origin server, delivers it to the user, and stores it in its cache for future requests. This process reduces latency and load on the origin server by serving repeated requests from edge caches.