Diagnosing Traffic Issues in Custom VPCs
Question
You are the administrator for your company.
You have set up Instances in a Custom VPC.
You have set the Security groups and Network ACLs for the Instances and subnets respectively.
The desired traffic is not reaching the instance.
You need to diagnose the issue and see why the traffic is not reaching the instance.
Which of the following would help in such a situation?
Answers
Explanations
Click on the arrows to vote for the correct answer
A. B. C. D.Correct Answer: B.
The AWS Documentation mentions the following.
VPC Flow Logs is a feature that enables you to capture information about the IP traffic going to and from network interfaces in your VPC.
Flow log data can be published to Amazon CloudWatch Logs and Amazon S3
After you've created a flow log, you can retrieve and view its data in the chosen destination.
Flow logs can help you with some tasks, for example, to troubleshoot why specific traffic is not reaching an instance, which helps you diagnose overly restrictive security group rules.
You can also use flow logs as a security tool to monitor the traffic reaching your instance.
Option A is incorrect since this will not provide you with detailed traffic logs.
Option C is incorrect since this is an API monitoring tool.
Option D is incorrect since this can only provide you recommendations but not tell you why the traffic is being blocked.
For more information on VPC Flow Logs, please refer to the below URL-
https://docs.aws.amazon.com/AmazonVPC/latest/UserGuide/flow-logs.htmlThe best option to diagnose the issue of traffic not reaching the instance in a Custom VPC is to use AWS VPC Flow Logs.
AWS VPC Flow Logs is a feature that enables the capture of IP traffic information for network interfaces in your VPC. The captured information includes the source and destination IP addresses, ports, protocol, packet and byte counts, and the start and end time of each flow.
Using VPC Flow Logs, you can identify and troubleshoot connectivity and security issues in your VPC by analyzing the captured traffic data. Specifically, you can use VPC Flow Logs to:
Troubleshoot connectivity issues: Analyze traffic flow logs to identify the source and destination of traffic that was not successful, and to check if there are any network access control list (ACL) rules or security group rules that may be blocking traffic.
Monitor and diagnose network performance: Analyze traffic flow logs to identify traffic patterns and usage statistics, and to identify and troubleshoot network performance issues.
Detect and investigate security breaches: Analyze traffic flow logs to identify suspicious traffic patterns or unexpected network activity, and to investigate potential security breaches.
In contrast, CloudWatch Logs is a feature that enables the monitoring and analysis of log data from AWS resources and applications. CloudTrail Logs is a feature that enables the capture of API activity and event data for your AWS account. While these services are useful for monitoring and troubleshooting AWS resources and applications, they are not specifically designed to diagnose connectivity issues in a VPC.
Finally, AWS Trusted Advisor is a service that provides guidance and recommendations to help optimize your AWS resources and applications, but it does not provide detailed network traffic analysis for VPCs.
In summary, the best option to diagnose the issue of traffic not reaching the instance in a Custom VPC is to use AWS VPC Flow Logs.
