Question

I have a web application that has been deployed to the AWS Mumbai region. My application soon becomes popular. Now there are users all over the world who would like to access it. If I use a CloudFront distribution for doing so, which statements are FALSE for CloudFront? (Select TWO.)

A. CloudFront uses the concept of Edge locations for caching and delivering content faster to its users.

B. CloudFront can help improve performance by using Keep-alive connections between the Edge locations &the origin server.

C. CloudFront does not cache dynamic content.

D. CloudFront can use only S3 buckets as their Origin Server from where they can cache content.

E. CloudFront can customize content at the Edge locations before delivering it to users

Answer 1

Answer: C, D.

Option A is incorrect.

CloudFront does use the concept of Edge locations for caching content that is requested by the user.

When a user in the US requests for content in a web server hosted in the Mumbai region, CloudFront will initially check whether the content is available at the nearest edge location in the US region.

If it is available, the content will be served directly from the Edge location.

If not, CloudFront will request the Origin Server, get the content and cache it at the Edge location for serving future requests.

Option B is incorrect.

Every HTTP connection runs on TCP/IP.

For every HTTP connection to work, a TCP handshake has to be initially completed.

Let's consider the following 2 scenarios.

i)

Two users without an Edge proxy - 1 Trip is 100ms.

We can see here that the total turnaround time for both users is 400ms.

ii)

Two users with a CloudFront Edge proxy.

We can see here that for the first user, the total turnaround time is 400ms, while for the second user, the total turnaround time is 240ms(4x20 + 2x80 )

Instead of re-establishing a second handshake with the Origin, CloudFront leverages the Keep-alive session resulting in reduced latency.

Option C is CORRECT since we can use the Time ToLive (TTL) value to enable caching of dynamic content.

Option D is CORRECT.

CloudFront has been opened to use Origin servers of your choice that can be S3 or a custom origin like EC2, ELB, etc...

Option E is incorrect.

CloudFront has the ability to customize content at the Edge location before delivering it to its users.