You have established a VPN connection between your on-premises and an AWS VPC.
You also need to ensure that instances in the VPC can reach the Internet.
So you have also attached an Internet gateway.
How would you set up the route tables to ensure that traffic can flow via the VPN and the Internet?
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A. B. C. D.Answer - B.
You should create a specific route for the Virtual Private gateway.
The AWS Documentation mentions the following.
You can use an AWS managed VPN connection to enable instances in your VPC to communicate with your own network.
To do this, create and attach a virtual private gateway to your VPC, and then add a route with the destination of your network and a target of the virtual private gateway (vgw-xxxxxxxx)
You can then create and configure your VPN connection.
Options A and D are invalid because you can only have one route table for a subnet.
Option C is invalid since you need to have a more specific route for the Virtual Private gateway.
For more information on Route tables, please refer to the below URL.
https://docs.aws.amazon.com/AmazonVPC/latest/UserGuide/VPC_Route_Tables.htmlSure, I can provide a detailed explanation of the correct answer.
The correct answer is B: Set up one route table. Add one route of 0.0.0.0/0 to the Internet and one specific prefix route for the Virtual Private gateway. Attach the Route table to the subnet in the VPC.
Let's break down why this is the correct answer.
Firstly, let's understand what a route table is. A route table is a set of rules, called routes, that are used to determine where network traffic is directed. Each subnet in a VPC must be associated with a route table, which controls the traffic routing for that subnet.
In this scenario, we have an on-premises network that is connected to an AWS VPC via a VPN connection. We also need to ensure that instances in the VPC can reach the Internet. To achieve this, we attach an Internet gateway to the VPC.
Now, we need to set up the route tables to ensure that traffic can flow via the VPN and the Internet. We need to ensure that traffic is routed to the Internet gateway when it is destined for the Internet, and to the virtual private gateway when it is destined for the on-premises network.
Option A suggests setting up two route tables: one with a default route to the Internet and another with the default route to the virtual private gateway. This option is not the best choice because it involves setting up multiple route tables, which can be confusing and difficult to manage.
Option C suggests setting up one route table with two default routes: one to the Internet and another to the virtual private gateway. This option is incorrect because having two default routes in the same route table can result in unpredictable routing behavior.
Option D suggests setting up two route tables: one with a default route to the Internet and another with a specific prefix route to the virtual private gateway. This option is also incorrect because it involves setting up multiple route tables, which can be confusing and difficult to manage.
Option B, on the other hand, suggests setting up one route table with one route to the Internet (0.0.0.0/0) and one specific prefix route for the virtual private gateway. This option is the best choice because it involves setting up a single route table with only the necessary routes, which is easier to manage and less prone to errors.
To summarize, to ensure that traffic can flow via the VPN and the Internet in a VPC, it is recommended to set up one route table with one route to the Internet (0.0.0.0/0) and one specific prefix route for the virtual private gateway, and attach the route table to the subnet in the VPC.