Exam AWS Certified Solutions Architect - Professional topic 1 question 35 discussion

ADE The question asks what will allow the application running inside the VPC to reach back and access its internal dependencies without being reconfigured. Not how to migrate it. To properly resolve internal dependency address you need Route53 https://docs.aws.amazon.com/Route53/latest/DeveloperGuide/resolver-getting-started.html

Answer is A,D,F B: Virtual and Customer gateway is needed C: Don’t need a EIP as private subnets can also interact with on-premises network E: Route 53 is not required

the question mention you have no knowledge to rebuild the app, so you need import the VM as a fundamental task

ADE E - Route 53 is required if the existing legacy app is using FQDN to access on-prem resources.

A. An AWS Direct Connect link between the VPC and the network housing the internal services. D. An IP address space that does not conflict with the one on-premises F. A VM Import of the current virtual machine

Don't understand how its anything but ADE. A. Only way mentioned to communicate with on prem. F. Can't work without it. Without a DNS resolver, the two machines will never find each other D. This is necessary for F to work. Wrong answers. B. It doesn't need to be public C. An elastic IP solve the problem of communicating with on Prem. F. Lots of ways to do this, but you only get three which are required for it to work.

Why everyone is so convinced about D? I would choose C over D, because an Elastic IP address comes from Amazon's pool of IPv4 addresses, !!!OR!!! from a custom IPv4 address pool that you have brought to your AWS account. Meaning that you can keep the IP from on-premise. ACF

Question is not on how to migrate the VM. The VM is assumed to have already been migrated. Resolution of address would require outbound endpoint and Rte 53 Resolver https://docs.aws.amazon.com/Route53/latest/DeveloperGuide/resolver.html

A. Possible for connection, if we do not have any other (better) way B. Wrong, the internet gateway is not for VNP. C. No, EIP is not needed. D. Yes, no IP conflict (or you need NAT) E. Good, I prefer hostnames over IPs F. Surely, for moving applications to the cloud. So choose three ADF; If choose four ADEF

I don't know why a lot of comments here are talking about route 53 when its not relevant at all. If we have a direct connect connection and a server that's migrated from on premise as is (including DNS config in /etc/resolv.conf ) That server will still use on premise DNS since we already have reachability to our on premise using direct connect You use route 53 resolver to point an ec2 instance that's using your VPC DNS to on premise The question is clearly asking for a "Lift and shift" approach so I would go with ADF

ADF ADF ADF ADF ADF

F and no E - We need to import the VM because we want to move all the configruations and keys that are located on its disk with it, so it is a must for the migration. Route53 is not a must!!!

https://docs.aws.amazon.com/Route53/latest/DeveloperGuide/resolver.html

ADE or ADF ADE : If you take the question "What enables the application operating inside the VPC to communicate with and access its internal dependencies without requiring reconfiguration?" In this case we assume the VM migaration is over ADF: If you focus on the question part "You've been entrusted with the responsibility of migrating a legacy application from a virtual machine" . here we assume the application uses hardcoded IP address and do not use DNS names

AD[E]. We are being asked for communication dependencies and NOT migration strategy! If the application is referencing internal/on-prem domains one would need to forward those to the on-prem DNS via R53. The facts we're given is there is "no documentation" about the app. So if the app could be configured to connect to an on-prem database or file server via a FQDN which is a best practice rather than reference IP's. So in this scenario how would you suggest it function if one does not leverage R53? Take another look at what we are being asked for... it is communication dependencies and not migration method!

ADE should be correct. Not F because the questionasks what will be required for the applicaton running inside the VPC (assumption that the application has already been migrated).

ADF Correct