AWS NAT Gateway Connectivity Verification
Question
You have created a NAT gateway to ensure that instances in your private subnet can download updates from the internet.
But the instances are still not able to reach the internet even after the gateway has been created.
Which of the following is not the right verification that needs to be carried out to diagnose the issue?
Answers
Explanations
Click on the arrows to vote for the correct answer
A. B. C. D.Answer - C.
The NAT gateway needs to be created in the public subnet and not the private subnet.
The AWS documentation mentions some of the below points which can be used to diagnose internet connectivity issues for EC2 Instances.
To troubleshoot instances that can't connect to the Internet from a private subnet using a NAT gateway, check the following:
Verify that the destination is reachable by pinging the destination from another source using a public IP address.
Verify that the NAT gateway is in the Available state.
Note: A NAT gateway in the Failed state is automatically deleted after about an hour.
Make sure that you've created your NAT gateway in a public subnet, and that that the public route table has a default route pointing to an Internet gateway.
Make sure that the private subnet's route table has a default route pointing to the NAT gateway.
Check that you have allowed the required protocols and ports for outbound traffic to the Internet.
For more information on EC2 Internet connectivity, please refer to the below link.
https://aws.amazon.com/premiumsupport/knowledge-center/ec2-internet-connectivity/When instances in a private subnet need to connect to the internet, they require a NAT gateway to forward the traffic to the internet. If the instances are unable to reach the internet after creating the NAT gateway, it could be due to several reasons, and the following verification steps can be performed to diagnose the issue:
A. Verify that the destination is reachable by pinging the destination from another source using a public IP address: This verification step is essential because it confirms whether the destination is reachable from the outside world. Pinging the destination from another source using a public IP address ensures that the internet connection is working correctly and that the issue is not with the destination.
B. Verify that the NAT gateway is in the Available state: The NAT gateway must be in the available state to function correctly. If it is not in the available state, it could indicate an issue with the NAT gateway or its configuration. Therefore, verifying that the NAT gateway is available is a crucial step in diagnosing the issue.
C. Verify that the NAT gateway has been created in the private subnet: This verification step is crucial because the NAT gateway must be created in the private subnet to allow instances to reach the internet. If the NAT gateway is created in the wrong subnet or the public subnet, instances in the private subnet will not be able to connect to the internet.
D. Make sure that the private subnet's route table has a default route pointing to the NAT gateway: This verification step is also essential because the instances in the private subnet can only access the internet through the NAT gateway if the route table for the subnet has a default route pointing to the NAT gateway. If the route table is not configured correctly, the instances will not be able to access the internet.
Therefore, based on the above explanations, the answer to the question is that all verification steps are essential, and there is no step that can be excluded when diagnosing the issue.
