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You are designing a multi-platform web application for AWS. The application will run on EC2
instances and will be accessed from PCs, tablets and smart phones, supported accessing
platforms are Windows, MacOS, IOS and Android. Separate sticky session and SSL certificate
setups are required for different platform types. Which of the following describes the most cost
effective and performance efficient architecture setup?

A.
Setup a hybrid architecture to handle session state and SSL certificates on-prem and separate
EC2 Instance groups running web applications for different platform types running in a VPC.

B.
Set up one ELB for all platforms to distribute load among multiple instance under it.
Each EC2 instance implements all functionality for a particular platform.

C.
Assign multiple ELBs to an EC2 Instance or group of EC2 instances running the common
components of the web application. One ELB for each platform type.
Session stickiness and SSL termination are done at the ELBs.

D.
Set up two ELBs. The first ELB handles SSL certificates for all platforms and the second ELB
handles session stickiness for all platforms.
For each ELB, run separate EC2 instance groups to handle the web application for each platform.

Explanation:
One ELB cannot handle different SSL certificates but since we are using sticky sessions it must
be handled at the ELB level. SSL could be handled on the EC2 instances only with TCP
configured ELB, ELB supports sticky sessions only in HTTP/HTTPS configurations.
The way the Elastic Load Balancer does session stickiness is on a HTTP/HTTPS listener is by
utilizing an HTTP cookie. If SSL traffic is not terminated on the Elastic Load Balancer and is
terminated on the back-end instance, the Elastic Load Balancer has no visibility into the HTTP
headers and therefore can not set or read any of the HTTP headers being passed back and forth.
http://docs.aws.amazon.com/ElasticLoadBalancing/latest/DeveloperGuide/elb-stickysessions.html

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