Can you please confirm me the answer to the following question? I gues for 1 answer is c, and for 2 answer is c. Please help.
1.An order processing website issuing EC2 instances to process messages from an SQS queue. A user reported an issue that their order was processed twice and hence charged twice. What action would you recommend ensuring this does not happen again? Choose the correct option
A. Insert code into the application to delete messages after processing
B. Increase the visibility timeout for the queue
C. Modify the order process to use SWF
D. Use long polling rather than short polling
2.You have EC2 instances in three availability zones, with a load balancer configured on all the three AZs. You observe that one availability zone is receiving more traffic as compared to other AZs, how can you solve this problem effectively
A. Disable sticky sessions
B. Reduce the frequency of the health checks
C. Enable cross zone load balancer
D. Amazon recommends to use two availability zone behind ELB
- A web company is looking to implement an external payment service into their highly available application deployed in a VPC. Their application EC2 instances are behind a public facing ELB. Auto scaling is used to add additional instances as traffic increases. Under normal load the application runs 2 instances in the Auto Scaling group but at peak it can scale 3x in size. The application instances need to communicate with the payment service over the Internet, which requires whitelisting of all public IP addresses used to communicate with it. A maximum of 4 whitelisting IP addresses are allowed at a time and can be added through an API. How should they architect their solution?
A. Route payment requests through two NAT instances setup for High Availability and whitelist the Elastic IP addresses attached to the NAT instances
B. Whitelist the VPC Internet Gateway Public IP and route payment requests through the Internet Gateway.
C. Whitelist the ELB IP addresses and route payment requests from the Application servers through the ELB.
D. Automatically assign public IP addresses to the application instances in the Auto Scaling group and run a script on boot that adds each instances public IP address to the payment validation whitelist API.