Troubleshooting Intermittent Connectivity Issues with Stateful Web Servers behind AWS Load Balancer
Question
You have created a load balancer in AWS with EC2 Instances behind them.
The ELB is serving web traffic to users on the Internet.
The Web servers behind the ELB are stateful.
Users begin to report intermittent connectivity issues when accessing the website.
What can be done to ensure that the issue is resolved?
Answers
Explanations
Click on the arrows to vote for the correct answer
A. B. C. D.Answer - C.
Option A is invalid because there is no mention of SSL in the question.
Option B is invalid because you should not allow access from anywhere on the EC2 Instances.
Option D is invalid because connection draining will not solve the issue.
The AWS Documentation mentions the following.
Sticky sessions are a mechanism to route requests to the same target in a target group.
This is useful for servers that maintain state information to provide a continuous experience to clients.
To use sticky sessions, the clients must support cookies.
For more information on sticky sessions for the ELB, please refer to the below URL on Page# 45 - Point# 9
https://docs.aws.amazon.com/elasticloadbalancing/latest/application/elb-ag.pdf#load-balancer-target-groupsWhen users report intermittent connectivity issues, it is important to investigate and resolve the issue as quickly as possible to avoid any impact on the application's availability and user experience.
In this scenario, where there is a load balancer serving web traffic to users on the internet and stateful web servers behind it, the following steps can be taken to resolve the issue:
Verify the health of the EC2 instances: Check the health of the EC2 instances behind the load balancer to ensure that they are healthy and responding to traffic. If any instance is unhealthy, it should be removed from the load balancer and investigated.
Check the load balancer logs: The load balancer logs can provide insight into the connections and requests being made to the EC2 instances. Analyzing the logs can help identify any patterns or issues with the traffic.
Enable access logging: Enable access logging on the load balancer to track the incoming requests and responses. The access logs can help identify the source of any errors or connectivity issues.
Enable sticky sessions: If the web servers are stateful and rely on session data, enabling sticky sessions at the target group level can help ensure that user requests are consistently routed to the same server instance, reducing the chances of session-related issues.
Enable connection draining: When an EC2 instance is removed from the load balancer, enabling connection draining ensures that any active connections are completed before the instance is terminated. This can help prevent connectivity issues caused by abrupt connection termination.
Option A and B are not relevant to this issue as they pertain to the security group configuration of the web servers and not the connectivity issue being reported.
Therefore, the correct answer is option C, enabling sticky sessions at the target group level, and option D, enabling connection draining.
