You have an environment that consists of a public subnet using Amazon VPC and 3
instances that are running in this subnet. These three instances can successfully
communicate with other hosts on the Internet. You launch a fourth instance in the same
subnet, using the same AMI and security group configuration you used for the others, but
find that this instance cannot be accessed from the Internet. What should you do to enable
internet access?
A.
Deploy a NAT instance into the public subnet.
B.
Modify the routing table for the public subnet
C.
Configure a publically routable IP Address In the host OS of the fourth instance.
D.
Assign an Elastic IP address to the fourth instance.
I have the same idea. D
d
Ans D
D.
The explain from A Cloud Guru:
This is the key to the question “You launch a fourth instance in the same subnet, using the same AMI and security group configuration you used for the others”
This means the issue is not related to AMI, SG and the subnet routing table.
Now have a look at the answer and remove the obvious incorrect one
A. Public subnet does not use NAT to access internet so this is obviously wrong
B. Routing table is not the root cause of the issue
Now we have left with C and D which both seems to make sense to be the correct answer. However, when you assign a public IP / EIP, you do not configure it in the host OS, instead you configure it in AWS console (or use API) and AWS will map (1:1 NAT) the public IP to the instance’s private IP, so answer C is wrong.
Therefore the correct answer is D.
D
D
D