You have a single Interconnect VLAN and Cloud Router in us-east1, and Compute instances in us-east1, us-west2, and us-central1. For high availability and cross-region subnet access if a region fails, what do you do cost-effectively?

The correct option ensures high availability and cross-region access by establishing a geographically redundant Interconnect connection. Setting VPC routing to global mode allows Cloud Routers in any region to advertise routes to all subnets in the VPC, enabling instances in us-east1 and us-central1 to reach on-premises resources via the us-west2 Interconnect if us-east1 fails. Adding an Interconnect VLAN attachment and Cloud Router in a different region (us-west2) provides this crucial redundancy. The other options are incorrect because: Adding another Interconnect in the same region (us-east1) doesn't provide cross-region failover. Setting VPC routing to regional mode restricts route advertisement to the local region, preventing cross-region subnet access during a regional outage. While adding Interconnects in all regions would provide redundancy, it's less cost-effective than a single additional Interconnect in a different region combined with global routing.