Exam Professional Cloud Architect topic 1 question 118 discussion

Correct Answer: A - IP Should not overlap so applying new IP address is the solution

Answer is C. https://cloud.google.com/network-connectivity/docs/router/how-to/advertising-custom-ip

This approach addresses the core problem of overlapping IP ranges: re-IP one of the networks (either the new company's VPC or your data center) so that there are no overlapping CIDR ranges. If IP ranges overlap, routers won't know which path to send traffic, leading to routing conflicts and connectivity failures. While Cloud NAT performs Network Address Translation, it's primarily designed for private instances to access the internet outbound. Using it to resolve overlapping internal IP ranges across a VPN tunnel adds significant complexity, management overhead, and can break certain types of connections. The best practice is to resolve the underlying IP overlap directly.

A is the best available option from the list, but in practice, you'd replace "apply new IP addresses" with implement a NAT gateway or proxy on one side to map the overlapping IP space to a non-overlapping range — preserving connectivity without re-IPing

https://cloud.google.com/nat/docs/overview#private-nat Assume that your Google Cloud resources in a VPC network need to communicate with destinations in a VPC, on-premises, or other cloud provider network that is owned by a different business unit. However, the destination network contains subnets whose IP addresses overlap with the IP addresses of your VPC network. In this scenario, you create a Cloud NAT gateway for Private NAT that translates traffic between the subnets in your VPC network to the non-overlapping subnets of the other network.

With A you need to apply new IP addresses, with B you can use private NAT.

Assume that the resources in your VPC network need to communicate with the resources in a VPC network or an on-premises or other cloud provider network that is owned by a different business unit. However, that network contains subnets whose IP addresses overlap with the IP addresses of your VPC network. In this scenario, you create a Private NAT gateway that translates traffic between the subnets in your VPC network to the non-overlapping subnets of the other network.

Correct Option: B. Create a Cloud VPN connection from the new VPC to the data center, and create a Cloud NAT instance to perform NAT on the overlapping IP space. This option effectively allows you to connect the two environments while addressing the overlapping IP space issue through NAT, ensuring that the VMs can communicate without conflicts.

There is a Private NAT you can use and is specifically designed to resolve overlapping private IP issues: https://medium.com/niveus-solutions/private-cloud-nat-and-why-we-need-it-on-gcp-f6ad0c96facb#:~:text=Private%20Cloud%20NAT%20with%20NCC,helps%20connect%20onprem%20to%20gcp.

Given that you are not going out to the internet and you need to use a Cloud Router for your VPC, you need to ensure that there is no overlap in the IP ranges between your data center and the newly acquired company's VPC. The best approach to manage this without renumbering the entire network is to use Network Address Translation (NAT) to handle the overlapping IP addresses.

would go for B

The answer is B. Cloud VPN and Cloud NAT help you get around this problem easily without all the work of creating a new subnet and reassigning IPs to everything. Cloud NAT: Network Address Translation (NAT) allows you to translate IP addresses in your VPC to a different IP range, avoiding conflicts with overlapping IP ranges in your data center. This ensures that traffic can flow between the environments without routing conflicts. Cloud VPN: Establishing a Cloud VPN connection provides secure connectivity between the new VPC and your data center. By combining this with Cloud NAT, you can effectively manage and resolve the IP address overlap.

Using Cloud NAT to translate overlapping IP addresses is the most effective solution to ensure seamless connectivity between the new company's VPC and your company's data center without routing conflicts. This approach avoids the complexity of reconfiguring IP addresses and ensures that both networks can communicate effectively. https://cloud.google.com/nat/docs/overview#private-nat

Ans is B

https://cloud.google.com/nat/docs/overview#private-nat Assume that the resources in your VPC network need to communicate with the resources in a VPC network or an on-premises or other cloud provider network that is owned by a different business entity. However, the VPC network of that business entity contains subnets whose IP addresses overlap with the IP addresses of your VPC network. In this scenario, you create a Private NAT gateway that routes traffic between the subnets in your VPC network to the non-overlapping subnets of that business entity.

I was absolutely sure that B was obviously wrong until I found that https://cloud.google.com/nat/docs/overview#private-nat So it seems like the answer is B...

The challenge with Option A is that changing IP addresses can be complex and might impact existing applications, configurations, and dependencies within the new company's VPC. It might introduce additional complexity and potential risks during the integration process. Option C, on the other hand, allows you to maintain the existing IP addressing in the new company's VPC while selectively blocking the overlapping IP space during the routing process. This can be a more flexible and less disruptive approach, especially in scenarios where readdressing is not practical. In summary, both options might have their use cases, but Option C provides a solution that doesn't require changing IP addresses and can help avoid potential disruptions caused by such changes.