This solution correctly addresses all three requirements outlined in the scenario. First, using AWS Lambda provisioned concurrency directly mitigates the cold start issue by keeping functions initialized and ready to respond instantly, ensuring low latency during traffic peaks. Second, for the database with consistent usage over 12 months, purchasing RDS Reserved Instances is the most cost-effective strategy, offering significant savings over On-Demand pricing. Third, integrating AWS WAF with Amazon CloudFront is the standard and most effective method to protect against common web exploits like SQL injection by filtering malicious traffic at the edge before it reaches the application.

A. Increasing a Lambda timeout does not solve cold starts. AWS Shield Advanced is primarily for DDoS protection, not for blocking application-layer attacks like SQL injection.

B. Amazon Redshift is a data warehouse, not a transactional (OLTP) database suitable for an ecommerce application. Amazon Inspector is a vulnerability scanner, not a web application firewall.

C. While provisioned concurrency is correct, AWS Shield Advanced is the wrong service for SQL injection protection. Also, for a consistent workload, RDS Reserved Instances are more cost-effective than Aurora Serverless.

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References:

1. AWS Lambda Provisioned Concurrency:

AWS Lambda Documentation, "Configuring provisioned concurrency": "Provisioned concurrency initializes a requested number of execution environments so that they are prepared to respond immediately to your function's invocations... a great way to ensure that your serverless application is highly responsive and can scale to meet expected demand without any cold starts."

Source: AWS Lambda Developer Guide, Section: "Managing concurrency for a Lambda function".

2. RDS Reserved Instances:

Amazon RDS Documentation, "Reserved DB instances for Amazon RDS": "Reserved DB instances give you the option to reserve a DB instance for a one- or three-year term and in turn receive a significant discount compared to the On-Demand DB instance pricing... We recommend Reserved DB instances for applications with steady-state usage."

Source: Amazon RDS User Guide, Section: "Billing for DB instances".

3. AWS WAF for SQL Injection:

AWS WAF Documentation, "How AWS WAF works": "AWS WAF is a web application firewall that lets you monitor the HTTP and HTTPS requests that are forwarded to your protected web application resources... You can configure conditions to look for, such as... the values in request headers, or strings that appear in requests that are likely to be malicious (such as SQL injection)."

Source: AWS WAF, AWS Firewall Manager, and AWS Shield Advanced Developer Guide, Section: "How AWS WAF works".

4. AWS Shield Advanced vs. AWS WAF:

AWS Shield Documentation, "AWS Shield Advanced": "For higher levels of protection against attacks, you can subscribe to AWS Shield Advanced... Shield Advanced provides expanded DDoS attack protection for your AWS resources." This confirms its primary purpose is DDoS mitigation, whereas WAF handles application-layer threats.

Source: AWS WAF, AWS Firewall Manager, and AWS Shield Advanced Developer Guide, Section: "AWS Shield Advanced".