Question 1mediummultiple choice
Full question →mediummultiple choiceObjective-mapped
A company hosts a multi-tier web application on AWS. The web tier runs on Amazon EC2 instances in a public subnet, and the database tier runs on Amazon EC2 instances in a private subnet. The security team needs to configure security groups to allow only the web tier instances to communicate with the database tier on port 3306 (MySQL). The web tier must be accessible from the internet on port 443. Which security group configuration meets these requirements?
Answer choices
Why each option matters
Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.
A
Best answer
Web security group: inbound rule allowing 0.0.0.0/0 on port 443. Database security group: inbound rule allowing the web security group as source on port 3306.
This is correct. The web SG allows internet traffic on port 443, and the database SG uses the web SG as a source, which permits only traffic from instances associated with the web SG on port 3306.
B
Distractor review
Web security group: inbound rule allowing 0.0.0.0/0 on port 443. Database security group: inbound rule allowing 0.0.0.0/0 on port 3306.
This is incorrect because opening the database SG to the entire internet (0.0.0.0/0) on port 3306 exposes the database to potential attacks from any source, violating security best practices.
C
Distractor review
Web security group: inbound rule allowing the web security group as source on port 443. Database security group: inbound rule allowing the web security group as source on port 3306.
This is incorrect because the web SG allows inbound traffic from itself (self-reference) on port 443, which does not allow internet traffic. Internet users cannot reach the web tier, so the application would be inaccessible.
D
Distractor review
Web security group: inbound rule allowing 0.0.0.0/0 on port 443. Database security group: inbound rule allowing the internet-facing Application Load Balancer security group as source on port 3306.
This is incorrect because the scenario does not mention an Application Load Balancer (ALB). Even if an ALB were present, the requirement is for direct communication between the web tier EC2 instances and the database tier, not through a load balancer.
Common exam trap
Common exam trap: authentication is not authorization
Logging in proves the user can authenticate. It does not automatically mean the user is allowed to enter privileged or configuration mode. Watch for AAA authorization, privilege level and command authorization details.
Technical deep dive
How to think about this question
This kind of question is testing the difference between identity and permission. A user may successfully log in to a router because authentication is working, but still fail to enter configuration mode because authorization is missing, misconfigured or mapped to a lower privilege level.
KKey Concepts to Remember
- Authentication checks who the user is.
- Authorization controls what the user is allowed to do after login.
- Privilege levels affect access to EXEC and configuration commands.
- AAA, TACACS+ and RADIUS can separate login success from command access.
TExam Day Tips
- Do not assume successful login means full administrative access.
- Look for words such as cannot enter configuration mode, privilege level, authorization or command access.
- Separate login problems from permission problems before choosing the answer.
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More questions from this exam
Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.
Question 1
A developer needs to launch a test server for a new application prototype. The developer logs into the AWS Management Console, selects an Amazon EC2 instance type, configures the security group, and starts the instance. The instance is running within two minutes, and the developer did not need to submit a formal request to the company's IT procurement team or wait for approval from a cloud administrator. Which essential characteristic of cloud computing does this scenario best demonstrate?
Question 2
A solutions architect is planning a new web application on AWS. The workload will include 3 Amazon EC2 instances (t3.medium) running 24/7, an Application Load Balancer, and an Amazon RDS for MySQL db.t3.small database. The architect needs to estimate the monthly cost for the first year, considering different purchasing options (On-Demand, 1-year All Upfront Reserved Instance, and Compute Savings Plan). Which AWS tool should the architect use to create this estimate?
Question 3
A company's development team frequently needs temporary test environments. A developer can log into the AWS Management Console, select an Amazon EC2 instance type, configure storage, and launch the instance within minutes without any interaction with the IT infrastructure team. This capability is an example of which essential characteristic of cloud computing?
Question 4
A company's finance team needs to analyze AWS spending in detail. They require a report that includes hourly cost data for each AWS service, each individual resource (e.g., a specific EC2 instance), and any cost allocation tags applied. The team plans to export this data to an Amazon S3 bucket and then import it into a custom business intelligence (BI) analytics dashboard. Which AWS tool should the finance team use to generate this level of detailed cost data?
Question 5
A company uses AWS for its development environment. The finance team wants to set a monthly budget of $10,000. They want to receive an email notification when the actual costs reach 80% of the budget ($8,000) and again when costs exceed the budget. The team needs a managed AWS service that can automatically send these alerts without requiring custom code or third-party tools. Which AWS service should the team use?
Question 6
A company uses AWS Organizations to manage multiple accounts. The security team needs to enforce a policy that restricts SSH access (port 22) from the internet (0.0.0.0/0) in all VPCs across all accounts. The team wants to centrally define the allowed rules and automatically apply them to newly created VPCs and security groups, while also automatically remediating any existing non-compliant security groups. Which AWS service should the team use?
FAQ
Questions learners often ask
What does this CLF-C02 question test?
Authentication checks who the user is.
What is the correct answer to this question?
The correct answer is: Web security group: inbound rule allowing 0.0.0.0/0 on port 443. Database security group: inbound rule allowing the web security group as source on port 3306. — Security groups act as virtual firewalls for EC2 instances. For the web tier, an inbound rule allowing HTTPS (port 443) from 0.0.0.0/0 is needed for internet access. For the database tier, the most secure approach is to reference the web tier's security group as the source for port 3306, ensuring only instances in that group can connect. This follows the principle of least privilege. The other options either allow unrestricted access to the database or incorrectly use self-references.
What should I do if I get this CLF-C02 question wrong?
Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.
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