Troubleshooting Web Application Accessibility Issue
Question
You currently manage a set of web servers hosted on EC2 Servers with public IP addresses.
These IP addresses are mapped to domain names.
There was an urgent maintenance activity that had to be carried out on the servers and the servers had to be stopped and started again.
Now the web application hosted on these EC2 Instances is not accessible via the domain names configured earlier.
Which of the following could be a reason for this?
Answers
Explanations
Click on the arrows to vote for the correct answer
A. B. C. D.Answer - D.
By default, the public IP address of an EC2 Instance is released after the instance is stopped and started.
Hence the earlier IP address which was mapped to the domain names would have become invalid now.
Options A, B and C are all invalid because these operations are not allowed in AWS.
For more information on public IP addressing, please visit the below URL:
http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-instance-addressing.html#concepts-public-addressesWhen an EC2 instance is stopped and started again, the public IP address associated with the instance might change. Therefore, the most probable reason for the web application hosted on these EC2 instances to become inaccessible via the domain names configured earlier is that the public IP addresses have changed after the instance was stopped and started.
Option A - The Route53 hosted zone doesn't need to be restarted. A hosted zone is a collection of DNS records that correspond to a domain name. If the domain name and its associated DNS records were previously correctly configured in Route53, they will continue to work even if the EC2 instances are stopped and started.
Option B - The network interfaces don't need to be initialized again. Initializing network interfaces might be required if there is an issue with network connectivity, but it is not related to the issue of the web application being inaccessible via the domain names.
Option C - The public IP addresses might need to be associated with the Elastic Network Interface (ENI) again if there was an issue with the association. However, if the public IP addresses were correctly associated with the ENI before the instance was stopped, it is unlikely that this association would have been lost after starting the instance again.
Therefore, the most probable reason is that the public IP addresses have changed after the instance was stopped and started. To fix this issue, the new public IP addresses need to be associated with the domain names in the DNS records using Route53 or any other DNS service.
