AWS Frequently Asked Questions (FAQ)

1. What should I do if I can’t connect to my EC2 instance?

Check whether ports 22/3389 are open in the security group, whether the instance has a public IP, and whether your local IP is whitelisted.

2. Why did my bill suddenly increase?

• EC2 instances kept running without being stopped
• Increased cross-region or outbound data transfer charges
• Spike in S3 requests or download volume
• CloudWatch logs were not cleaned up

3. Region selection recommendations

Common choices for users in China are Singapore and Tokyo. US regions generally offer the lowest overall pricing.

4. Will I be charged after stopping an EC2 instance?

Stopped instances are not billed for compute, but EBS volumes, Elastic IPs, and snapshots may still incur charges.

5. Recommended instances for beginners

t3.micro / t3.small provide stable performance and are suitable for light workloads and test environments.

6. What if I lose my key pair?

You can log in using EC2 Instance Connect or SSM Session Manager.

7. Security group vs. firewall

Security groups operate at the AWS network layer, while firewalls operate within the operating system. They work at different layers.

8. Is Elastic IP (EIP) charged?

EIPs are charged when not associated with a running instance; they are generally free when attached and in use.

9. How can I prevent crypto-mining attacks?

Disable password login, enable MFA, restrict security group sources, and enable GuardDuty for detection.

10. Website not accessible: troubleshooting steps

• Check domain DNS records and resolution status
• Confirm required ports are open in the security group
• Verify Nginx/Apache is running properly
• Check server CPU and memory usage
• Review application errors and logs