Examkin

Question

Difficulty: Very hardPlanning Virtual Private Cloud (VPC) Networks and Subnets

A global enterprise is designing a multi-region Google Cloud Virtual Private Cloud (VPC) network to connect workloads in us−central1us-central1 and europe−west1europe-west1 to two existing on-premises datacenters (10.100.0.0/1610.100.0.0/16 and 10.200.0.0/1610.200.0.0/16) via Cloud VPN. To prevent IP address exhaustion and ensure future subnet expansion can occur seamlessly without routing conflicts, which TWO architecture and design decisions must the cloud network engineer enforce during initial VPC creation?

  1. Provision the VPC network in custom mode and manually assign explicit, non-overlapping regional primary IP ranges.Answer
  2. Reserve contiguous unused IP address blocks adjacent to primary subnet ranges to allow expand-in-place operations.Answer
  3. C
    Deploy the network as an auto-mode VPC to automatically allocate contiguous /16/16 CIDR blocks across all Google Cloud regions.
  4. D
    Configure subnets with primary IP ranges that overlap with the on-premises range 10.100.0.0/1610.100.0.0/16 to minimize external routing table size.

Answer

The correct architecture decisions are to provision the VPC network in custom mode with explicit non-overlapping regional primary IP ranges, and to reserve contiguous unused IP space adjacent to primary subnets for future expansion.
Custom-mode VPC networks give network architects full control over IP CIDR range allocation, ensuring that Google Cloud subnets do not conflict with on-premises CIDRs. Furthermore, leaving contiguous unused IP space adjacent to primary subnets ensures that subnets can be expanded in place without causing address overlap.

Step-by-Step Solution

1
Analyze network mode requirements for enterprise hybrid connectivity.
Auto-mode VPC networks allocate predefined /20/20 subnets in every region from 10.128.0.0/910.128.0.0/9, creating high risk of IP overlap with internal networks. Custom mode must be used for enterprise hybrid deployments.
Custom mode allows precise specification of subnet CIDR blocks to avoid conflicts with on-premises ranges such as 10.100.0.0/1610.100.0.0/16 and 10.200.0.0/1610.200.0.0/16.
2
Evaluate expansion constraints for VPC subnets.
Subnet expansion in GCP requires expanding the netmask of the existing primary CIDR block (e.g., from /24/24 to /23/23).
If adjacent IP address space is already assigned to another subnet or network resource, expanding the netmask will fail due to CIDR overlap.

Key Concept

Planning Custom Mode VPC Networks and Subnet CIDR Allocation for Hybrid Architecture
Estimated Time:2m 0s
Rate this question

Topics

Planning Virtual Private Cloud (VPC) Networks and Subnets

More questions from this topic