You have the following routing design. You discover that Compute Engine instances in Subnet-2 in the asia-southeast1 region cannot communicate with compute resources on-premises. What should you do?

Question

Exhibit

Options

• AConfigure a custom route advertisement on the Cloud Router.
• BEnable IP forwarding in the asia-southeast1 region.
• CChange the VPC dynamic routing mode to Global.
• DAdd a second Border Gateway Protocol (BGP) session to the Cloud Router.

• A
  13% (4)
• B
  9% (3)
• C
  75% (24)
• D
  3% (1)

Explanation

In the default Regional dynamic routing mode, a Cloud Router only propagates learned BGP routes (from on-premises) to subnets within its own region. If the Cloud Router and VPN gateway are in a different region than asia-southeast1, the on-premises routes will not be distributed to instances in Subnet-2 in asia-southeast1, causing the connectivity failure. Switching to Global dynamic routing mode causes the Cloud Router to advertise all VPC subnets to on-premises and distribute all learned on-premises routes to all regions across the entire VPC, resolving the issue. Option A would not fix the problem since the BGP sessions are presumably already advertising the correct routes. Option B (IP forwarding) enables VMs to act as routers, which is unrelated to this issue. Option D adding a second BGP session does not fix regional route propagation.

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