Well-Architected Framework: CLF-C02 study notes and practice questions
What to know about Well-Architected Framework for the CLF-C02 exam, from the Cloud Concepts domain (24% of the exam guide), then 4 free questions to test it. Part of the CLF-C02 study guide.
The Well-Architected Framework is AWS’s set of best practices for building on AWS. Exam questions give you a design principle or a goal and ask which pillar it belongs to.
The six pillars
Pillar
About
Example design principles
Operational excellence
Running and improving workloads
Perform operations as code, make frequent small reversible changes, anticipate failure, learn from operational events
Security
Protecting data, systems and assets
Implement a strong identity foundation, enable traceability, apply security at all layers, protect data in transit and at rest, keep people away from data
Reliability
Working correctly and recovering from failure
Automatically recover from failure, test recovery procedures, scale horizontally, stop guessing capacity, manage change through automation
Performance efficiency
Using resources efficiently as demand changes
Democratize advanced technologies, go global in minutes, use serverless architectures, experiment more often
Cost optimization
Delivering value at the lowest price
Adopt a consumption model, measure overall efficiency, stop spending on undifferentiated heavy lifting, analyze and attribute expenditure
Sustainability
Reducing environmental impact
Understand your impact, maximize utilization, use managed services, reduce the downstream impact of your workloads
Tools
AWS Well-Architected Tool in the console lets you review a workload against the pillars and track improvements.
Well-Architected Lenses add guidance for specific workloads such as serverless or machine learning.
AWS Trusted Advisor checks your account for best-practice gaps in several of the same areas (cost, performance, security, fault tolerance, service limits).
Sustainability is shared
AWS is responsible for the sustainability of the cloud (efficient data centers, renewable energy). Customers are responsible for sustainability in the cloud (right-sizing, turning off idle resources, choosing efficient services).
Common traps
Reliability vs performance efficiency. “Recover automatically” and “scale horizontally to increase availability” are reliability; “use the right resource type” and “go global” are performance efficiency.
Operational excellence vs reliability. Running procedures as code and learning from incidents is operational excellence.
Forgetting sustainability. It is the sixth pillar, added in 2021, and it appears on the exam.
An architect reviews a payments workload and finds three gaps.
Engineers have standing access to production customer data, some changes cannot be traced back to a named person, and several services share one administrator identity.
Which pillar of the AWS Well-Architected Framework contains the design principles that address these gaps?
Choose one answer.
AA. Reliability, covering recovery from failures and scaling to meet demand
BB. Security, covering identity, traceability and protecting data
CC. Operational Excellence, covering running and improving workloads through code and frequent change
DD. Cost Optimization, covering spending only on what the business needs
Show the answer and explanation
Answer: B
A. Wrong: Reliability covers recovering from failures and scaling to meet demand. Its principles would help availability, but not the access and traceability gaps described in the review.
C. Wrong: Operational Excellence covers running and improving workloads through code, small reversible changes and learning from events. Logging touches it, but the access gaps are primarily security principles.
D. Wrong: Cost Optimization covers controlling and measuring spend. Shared identities and standing access are not cost concerns, so this pillar does not contain the principles the architect needs.
Explanation
The three gaps match Security pillar design principles: implement a strong identity foundation, maintain traceability, and keep people away from data. Reliability, Operational Excellence and Cost Optimization cover other concerns, even though some of their practices touch on logging or change.
A company runs several AWS accounts, and nobody reviews them on a regular basis.
It wants AWS to check the accounts automatically against best practices and recommend ways to save money, close security gaps or improve availability, without installing any tools.
Which AWS service provides these checks?
Choose one answer.
AA. AWS Trusted Advisor, which checks accounts against best practices and recommends fixes
BB. AWS Config, which records resource configurations and evaluates them against rules
CC. AWS Cost Explorer, which charts past spending and forecasts future costs by service and account
DD. AWS Artifact, which provides on-demand compliance reports and agreements with AWS
Show the answer and explanation
Answer: A
A. Right: Correct. Trusted Advisor inspects the AWS environment and makes recommendations when there are opportunities to save money, improve availability and performance, or close security gaps. Learn more: AWS Trusted Advisor (opens in a new tab)
B. Wrong: AWS Config records resource configurations and evaluates them against rules, but the company must choose and maintain those rules. It does not produce a set of best-practice recommendations across savings, security and availability.
C. Wrong: Cost Explorer charts past spending and forecasts future costs. It helps with spend analysis only, and does not check security or availability settings.
D. Wrong: AWS Artifact gives access to AWS compliance reports and agreements. It does not inspect the company's own accounts or make recommendations about them.
Explanation
AWS Trusted Advisor inspects a customer's AWS environment against AWS best practices and recommends ways to save money, improve availability and performance, or close security gaps. Config, Cost Explorer and Artifact each cover a narrower part of that job.
A company's sustainability team wants to reduce the environmental impact of the AWS workloads it runs.
It is reviewing the Sustainability pillar of the AWS Well-Architected Framework to decide which actions fall to the company, and which are handled by AWS in its data centers.
Which action is the company's responsibility?
Choose one answer.
AA. Optimizing workloads and resource use so that fewer resources need to be deployed
BB. Sourcing renewable power for the data centers that run AWS services
CC. Practicing water stewardship at the facilities that host AWS infrastructure
DD. Designing efficient shared infrastructure inside AWS data centers
B. Wrong: Incorrect. Sourcing renewable power is part of sustainability of the cloud, which AWS is responsible for across its data centers. Customers do not choose the energy supply for AWS facilities.
C. Wrong: Incorrect. Water stewardship at AWS facilities is part of sustainability of the cloud, and AWS is responsible for it. A customer does not manage water use at those sites.
D. Wrong: Incorrect. Efficient shared infrastructure inside AWS data centers is AWS's responsibility. Customers can still design their own workloads to use that infrastructure efficiently.
Explanation
The Sustainability pillar splits responsibility. AWS is responsible for sustainability of the cloud, including renewable power, water stewardship and efficient shared infrastructure. Customers are responsible for sustainability in the cloud, which means optimizing their own workloads and resource use.
A video platform team plans to change instance families and storage types regularly to test which performs best.
It wants to use managed machine learning services instead of building that expertise itself, and it moves its image-resizing code to serverless functions so that it does not manage servers.
Which Well-Architected pillar's design principles does the team follow?
Choose one answer.
AA. Cost Optimization, covering spend control and paying only for what the business needs
BB. Reliability, covering recovery from failures and scaling to meet demand
CC. Operational Excellence, covering running and improving workloads through code and small changes
DD. Performance Efficiency, covering using technology and resources efficiently as needs change
Show the answer and explanation
Answer: D
A. Wrong: Cost Optimization focuses on spending only what the business needs and on measuring that spend. Testing instance types relates to cost, but the scenario is mainly about experimenting, managed services and data access patterns.
B. Wrong: Reliability covers recovering from failures and scaling to meet demand. The team's choices concern performance and technology selection, not recovering from failure.
C. Wrong: Operational Excellence covers running and improving workloads through code, small reversible changes and learning from events. Frequent experiments touch it, but managed ML services and serverless functions are performance decisions.
The Performance Efficiency design principles include experimenting more often, democratizing advanced technologies by consuming them as managed services, and using serverless architectures. Those match the team's three plans. The other pillars cover cost, failure recovery and operations.
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