Amazon Virtual Private Cloud (VPC) | ClassicLink Flashcards
Are there AWS Services that cannot be used over Inter-Region VPC Peering?
ClassicLink
Amazon Virtual Private Cloud (VPC) | Networking & Content Delivery
Network Load Balancers, AWS PrivateLink and Elastic File System cannot be used over Inter-Region VPC Peering.
What is ClassicLink?
ClassicLink
Amazon Virtual Private Cloud (VPC) | Networking & Content Delivery
Amazon Virtual Private Cloud (VPC) ClassicLink allows EC2 instances in the EC2-Classic platform to communicate with instances in a VPC using private IP addresses. To use ClassicLink, enable it for a VPC in your account, and associate a Security Group from that VPC with an instance in EC2-Classic. All the rules of your VPC Security Group will apply to communications between instances in EC2-Classic and instances in the VPC.
What does ClassicLink cost?
ClassicLink
Amazon Virtual Private Cloud (VPC) | Networking & Content Delivery
There is no additional charge for using ClassicLink; however, existing cross Availability Zone data transfer charges will apply. For more information, consult the EC2 pricing page.
How do I use ClassicLink?
ClassicLink
Amazon Virtual Private Cloud (VPC) | Networking & Content Delivery
In order to use ClassicLink, you first need to enable at least one VPC in your account for ClassicLink. Then you associate a Security Group from the VPC with the desired EC2-Classic instance. The EC2-Classic instance is now linked to the VPC and is a member of the selected Security Group in the VPC. Your EC2-Classic instance cannot be linked to more than one VPC at the same time.
Does the EC2-Classic instance become a member of the VPC?
ClassicLink
Amazon Virtual Private Cloud (VPC) | Networking & Content Delivery
The EC2-Classic instance does not become a member of the VPC. It becomes a member of the VPC Security Group that was associated with the instance. All the rules and references to the VPC Security Group apply to communication between instances in EC2-Classic instance and resources within the VPC.
Can I use EC2 public DNS hostnames from my EC2-Classic and EC2-VPC instances to address each other, in order to communicate using private IP?
ClassicLink
Amazon Virtual Private Cloud (VPC) | Networking & Content Delivery
No. The EC2 public DNS hostname will not resolve to the private IP address of the EC2-VPC instance when queried from an EC2-Classic instance, and vice-versa.
Are there any VPCs for which I cannot enable ClassicLink?
ClassicLink
Amazon Virtual Private Cloud (VPC) | Networking & Content Delivery
Yes. ClassicLink cannot be enabled for a VPC that has a Classless Inter-Domain Routing (CIDR) that is within the 10.0.0.0/8 range, with the exception of 10.0.0.0/16 and 10.1.0.0/16. In addition, ClassicLink cannot be enabled for any VPC that has a route table entry pointing to the 10.0.0.0/8 CIDR space to a target other than “local”.
Can traffic from an EC2-Classic instance travel through the Amazon VPC and egress through the Internet gateway, virtual private gateway, or to peered VPCs?
ClassicLink
Amazon Virtual Private Cloud (VPC) | Networking & Content Delivery
Traffic from an EC2-Classic instance can only be routed to private IP addresses within the VPC. They will not be routed to any destinations outside the VPC, including Internet gateway, virtual private gateway, or peered VPC destinations.
Does ClassicLink affect the access control between the EC2-Classic instance, and other instances that are in the EC2-Classic platform?
ClassicLink
Amazon Virtual Private Cloud (VPC) | Networking & Content Delivery
ClassicLink does not change the access control defined for an EC2-Classic instance through its existing Security Groups from the EC2-Classic platform.
Will ClassicLink settings on my EC2-Classic instance persist through stop/start cycles?
ClassicLink
Amazon Virtual Private Cloud (VPC) | Networking & Content Delivery
The ClassicLink connection will not persist through stop/start cycles of the EC2-Classic instance. The EC2-Classic instance will need to be linked back to a VPC after it is stopped and started. However, the ClassicLink connection will persist through instance reboot cycles.
Will my EC2-Classic instance be assigned a new, private IP address after I enable ClassicLink?
ClassicLink
Amazon Virtual Private Cloud (VPC) | Networking & Content Delivery
There is no new private IP address assigned to the EC2-Classic instance. When you enable ClassicLink on an EC2-Classic instance, the instance retains and uses its existing private IP address to communication with resources in a VPC.
