Google Professional Cloud Network Engineer Exam Questions

The correct answer is D because it meets the following requirements:

It matches the hub-and-spoke model of the on-premises network, where each spoke is a separate VPC network that is connected to a central hub VPC network.

It minimizes management overhead and cost, because VPC Network Peering is a simple and low-cost way to connect VPC networks without using any external IP addresses or VPN gateways1.

It uses default networking quotas and limits, because VPC Network Peering does not consume any quota or limit for VPN tunnels, external IP addresses, or forwarding rules2.

It prevents connectivity between the spokes, because VPC Network Peering is non-transitive by default, meaning that a spoke can only communicate with the hub, not with other spokes1.To enforce this restriction, a third-party network appliance can be used as a default gateway in each spoke VPC network, which can filter out any traffic destined for other spokes3.

Option A is incorrect because it does not minimize cost, as Cloud VPN charges for egress traffic and requires external IP addresses for the VPN gateways4.Option B is incorrect because it does not prevent connectivity between the spokes, as VPC Network Peering allows direct communication between peered VPC networks by default1. Option C is incorrect because it does not minimize cost or use default quotas and limits, for the same reasons as option A.

VPC Network Peering overview | VPC

Quotas and limits | VPC

Hub-and-spoke network architecture | Cloud Architecture Center

Cloud VPN overview | Google Cloud

Understanding VPC Flow Logs:

VPC Flow Logs is a feature that captures information about the IP traffic going to and from network interfaces in a VPC. It helps in monitoring and analyzing network traffic, ensuring security, and optimizing network performance.

Current Configuration:

According to the diagram, VPC Flow Logs is already configured for Subnet-1 in the host VPC. This means that traffic information for Subnet-1 is being captured and logged.

Requirement for Subnet-2:

The goal is to monitor flow logs for Subnet-2, which is in the service project VPC.

Correct Configuration for Subnet-2:

To monitor the flow logs for Subnet-2, you need to configure VPC Flow Logs within the service project VPC where Subnet-2 resides. This is because VPC Flow Logs must be configured in the same project and VPC where the subnet is located.

Implementation Steps:

Go to the Google Cloud Console.

Navigate to the service project where Subnet-2 is located.

Select the VPC network containing Subnet-2.

Enable VPC Flow Logs for Subnet-2 by editing the subnet settings and enabling the flow logs option.

Cost and Performance Considerations:

Enabling VPC Flow Logs may incur additional costs based on the volume of data logged. Ensure to review and understand the pricing implications.

Analyze and manage the data collected to avoid unnecessary logging and costs.

Google Cloud VPC Flow Logs Documentation

Configuring VPC Flow Logs

Shared VPC Overview

By configuring VPC Flow Logs in the service project VPC for Subnet-2, you ensure that traffic data is correctly captured and monitored, adhering to Google Cloud's best practices.

The correct answer is D because it meets the following requirements:

It matches the hub-and-spoke model of the on-premises network, where each spoke is a separate VPC network that is connected to a central hub VPC network.

It minimizes management overhead and cost, because VPC Network Peering is a simple and low-cost way to connect VPC networks without using any external IP addresses or VPN gateways1.

It uses default networking quotas and limits, because VPC Network Peering does not consume any quota or limit for VPN tunnels, external IP addresses, or forwarding rules2.

It prevents connectivity between the spokes, because VPC Network Peering is non-transitive by default, meaning that a spoke can only communicate with the hub, not with other spokes1.To enforce this restriction, a third-party network appliance can be used as a default gateway in each spoke VPC network, which can filter out any traffic destined for other spokes3.

Option A is incorrect because it does not minimize cost, as Cloud VPN charges for egress traffic and requires external IP addresses for the VPN gateways4.Option B is incorrect because it does not prevent connectivity between the spokes, as VPC Network Peering allows direct communication between peered VPC networks by default1. Option C is incorrect because it does not minimize cost or use default quotas and limits, for the same reasons as option A.

VPC Network Peering overview | VPC

Quotas and limits | VPC

Hub-and-spoke network architecture | Cloud Architecture Center

Cloud VPN overview | Google Cloud

Understanding VPC Flow Logs:

VPC Flow Logs is a feature that captures information about the IP traffic going to and from network interfaces in a VPC. It helps in monitoring and analyzing network traffic, ensuring security, and optimizing network performance.

Current Configuration:

According to the diagram, VPC Flow Logs is already configured for Subnet-1 in the host VPC. This means that traffic information for Subnet-1 is being captured and logged.

Requirement for Subnet-2:

The goal is to monitor flow logs for Subnet-2, which is in the service project VPC.

Correct Configuration for Subnet-2:

To monitor the flow logs for Subnet-2, you need to configure VPC Flow Logs within the service project VPC where Subnet-2 resides. This is because VPC Flow Logs must be configured in the same project and VPC where the subnet is located.

Implementation Steps:

Go to the Google Cloud Console.

Navigate to the service project where Subnet-2 is located.

Select the VPC network containing Subnet-2.

Enable VPC Flow Logs for Subnet-2 by editing the subnet settings and enabling the flow logs option.

Cost and Performance Considerations:

Enabling VPC Flow Logs may incur additional costs based on the volume of data logged. Ensure to review and understand the pricing implications.

Analyze and manage the data collected to avoid unnecessary logging and costs.

Google Cloud VPC Flow Logs Documentation

Configuring VPC Flow Logs

Shared VPC Overview

By configuring VPC Flow Logs in the service project VPC for Subnet-2, you ensure that traffic data is correctly captured and monitored, adhering to Google Cloud's best practices.

This answer follows the Google-recommended practices for using privately used public IP (PUPI) addresses for GKE Pod address blocks1. The benefits of this approach are:

It allows you to use any public IP addresses that are not owned by Google or your organization for your Pods, which can help mitigate address exhaustion in your enterprise.

It prevents any external traffic from reaching your Pods, as Google Cloud does not route PUPI addresses to the internet or to other VPC networks by default.

It enables you to use VPC Network Peering to connect your GKE cluster to other VPC networks that use different PUPI addresses, as long as you enable the export and import of custom routes for the peering connection.

It preserves the fully integrated network model of GKE, where Pods can communicate with nodes and other resources in the same VPC network without NAT.

The options that you need to select when creating a private GKE cluster with PUPI addresses are:

--disable-default-snat: This option disables source NAT for outbound traffic from Pods to destinations outside the cluster's VPC network.This is necessary to prevent Pods from using RFC 1918 addresses as their source IP addresses, which could cause conflicts with other networks that use the same address space2.

--enable-ip-alias: This option enables alias IP ranges for Pods and Services, which allows you to use separate subnet ranges for them.This is required to use PUPI addresses for Pods1.

--enable-private-nodes: This option creates a private cluster, where nodes do not have external IP addresses and can only communicate with the control plane through a private endpoint.This enhances the security and privacy of your cluster3.

Option A is incorrect because it does not use PUPI addresses for Pods, but rather RFC 1918 addresses. This does not solve the problem of address exhaustion in your enterprise. Option B is incorrect because it reuses the secondary address range for Services across multiple private GKE clusters, which could cause IP conflicts and routing issues. Option C is incorrect because it does not specify the options that are needed to create a private GKE cluster with PUPI addresses.

1:Configuring privately used public IPs for GKE | Kubernetes Engine | Google Cloud2:Using Cloud NAT with GKE | Kubernetes Engine | Google Cloud3:Private clusters | Kubernetes Engine | Google Cloud