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Zorluk: OrtaVPC Connectivity and Routing Troubleshooting

A SysOps administrator has launched an Amazon EC2 instance in a new subnet to host a public web server. The instance has been assigned a public IPv4 address, and its associated security group is configured to allow outbound traffic to 0.0.0.0/00.0.0.0/0 and inbound HTTP/HTTPS traffic on ports 8080 and 443443. However, users cannot access the web server from the internet, and the instance is unable to communicate with any external resources. Which of the following troubleshooting steps should the administrator perform to resolve this connectivity issue? (Select TWO.)

  1. Verify that the subnet's route table contains a route for 0.0.0.0/00.0.0.0/0 targeting the attached Internet Gateway.Cevap
  2. Verify that the Network ACL associated with the subnet has an outbound rule allowing traffic to 0.0.0.0/00.0.0.0/0 and an inbound rule allowing return traffic on ephemeral ports (1024655351024-65535).Cevap
  3. C
    Modify the instance's security group to allow inbound traffic from ephemeral ports (1024655351024-65535) to accommodate the return path.
  4. D
    Deploy a NAT gateway in the subnet and add a route targeting the NAT gateway for 0.0.0.0/00.0.0.0/0 in the subnet's route table.
  5. E
    Create a Gateway VPC Endpoint for the Internet Gateway and associate it with the subnet's route table.

Cevap

Verify that the subnet's route table contains a route for 0.0.0.0/00.0.0.0/0 targeting the attached Internet Gateway, and verify that the Network ACL associated with the subnet has an outbound rule allowing traffic to 0.0.0.0/00.0.0.0/0 and an inbound rule allowing return traffic on ephemeral ports (1024655351024-65535).
To make a subnet public and allow bidirectional internet communication for an EC2 instance with a public IP, the subnet's route table must have a route for 0.0.0.0/00.0.0.0/0 pointing to an Internet Gateway. Additionally, because Network ACLs are stateless, they must be explicitly configured to allow outbound traffic to 0.0.0.0/00.0.0.0/0 and inbound return traffic on ephemeral ports (1024655351024-65535) to complete the connection handshake.

Adım Adım Çözüm

1
Examine the route table associated with the subnet where the EC2 instance is deployed.
Ensure that a route for destination 0.0.0.0/00.0.0.0/0 is present and targets the Internet Gateway.
Without this route, the subnet remains private, and internet traffic to and from the public IP address cannot be routed.
2
Examine the Network ACL rules associated with the subnet.
Ensure that outbound rules allow traffic to the internet and inbound rules permit return traffic on ephemeral ports (1024655351024-65535).
Network ACLs are stateless, meaning return traffic must be explicitly allowed.

Anahtar Kavram

VPC public routing and stateless network filtering troubleshooting
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