Your VPC consists of public and private subnets. The private subnets make use of NAT Gateway to download updates from the internet. The Instances are trying to download updates from a server that listens on port 8090. But the instances are not able to reach the external server for updates. Which of the following could be relevant issues with this? (Select THREE)

Answer options:

A.The NAT Gateway is blocking traffic on port 8090.
B.The Inbound NACL is blocking traffic on port 8090.
C.The Inbound Security Groups are blocking traffic on port 8090.
D.The remote server firewall is blocking traffic.

Answer - A, B, and D
The NAT instance could be blocking Outbound Traffic on port 8090 which is not allowing traffic to flow outwards.
The remote server could also be blocking traffic from the instances.
Option B is CORRECT because NACL inbound rule must allow ephemeral ports for outbound traffic
Option C is INCORRECT because the server already listens on port 8090 and since security groups are stateful, even the outbound would be allowed on port 8090.
Option D is CORRECT because the question is asking for "relevant issues" and therefore the firewall can also be considered here
For more information on NAT Instances, please visit the below URL
https://docs.aws.amazon.com/AmazonVPC/latest/UserGuide/VPC_NAT_Instance.html