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When troubleshooting connectivity issues, especially over public internet connections with intermittent errors, Connectivity Tests in Network Intelligence Center are crucial. This tool allows you to simulate the connectivity and understand the data plane status of Google Cloud resources. Since ICMP tests pass but TCP tests fail intermittently, using Connectivity Tests with TCP parameters will provide detailed insight into possible network issues like route misconfigurations, peering issues, or other transient problems affecting only specific protocols.

Overview By creating and managing SSH keys, you can let users access a Linux instance through third-party tools. An SSH key consists of the following files: A public SSH key file that is applied to instance-level metadata or project-wide metadata. A private SSH key file that the user stores on their local devices. If a user presents their private SSH key, they can use a third-party tool to connect to any instance that is configured with the matching public SSH key file, even if they aren't a member of your Google Cloud project. Therefore, you can control which instances a user can access by changing the public SSH key metadata for one or more instances. https://cloud.google.com/compute/docs/instances/adding-removing-ssh-keys#addkey

"TFTP is a UDP-based protocol. Servers listen on port 69 for the initial client-to-server packet to establish the TFTP session, then use a port above 1023 for all further packets during that session. Clients use ports above 1023" https://docstore.mik.ua/orelly/networking_2ndEd/fire/ch17_02.htm Besides, Google Cloud external TCP/UDP Network Load Balancing (after this referred to as Network Load Balancing) is a regional, non-proxied load balancer. Network Load Balancing distributes traffic among virtual machine (VM) instances in the same region in a Virtual Private Cloud (VPC) netw

The key requirements are: limited IP space (192.168.0.0/20), reaching on-premises (172.16.0.0/16) from multiple Google Cloud regions (us-west1, europe-central1, asia-southeast1), and minimizing IP addresses used. The Cloud Interconnect connection to on-premises is in us-east4.

Minimize IP addresses and centralized NAT: Since all traffic to on-premises will traverse the Cloud Interconnect in us-east4, it's most efficient to configure a single Private NAT gateway instance in us-east4. This allows resources from other regions to egress to on-premises through this single NAT gateway, using a minimal NAT subnet (192.168.1.0/24 in this case), thus conserving the limited 192.168.0.0/20 IP space.

Network Connectivity Center Spoke Export Policy: The VPC spoke needs to advertise the NAT subnet to the Network Connectivity Center hub. An export include policy is used to specify which routes (in this case, the 192.168.1.0/24 NAT subnet) should be advertised to the hub.

Global Dynamic Routing: To allow resources in us-west1, europe-central1, and asia-southeast1 to reach the on-premises location through the us-east4 Cloud Interconnect and NAT gateway, the VPC containing these resources (the spoke VPC) must have global dynamic routing enabled. This ensures that routes learned in one region (like the on-premises routes via us-east4) are available to VMs in all other regions of that VPC.

Options A and B configure Private NAT gateways in multiple regions, which consumes more IP addresses than necessary given that the Cloud Interconnect is only in us-east4. Option D uses 172.16.x.x for NAT subnets, which clashes with the on-premises IP range and the requirement to use the 192.168.0.0/20 space for cloud.

Exact Extract:

"Private NAT allows instances with private IP addresses in one VPC network to connect to on-premises or other cloud networks through a NAT IP address in a different region or network."

"To allow VMs in multiple regions to reach a central destination through a NAT gateway located in a specific region, you must configure global dynamic routing on the VPC network. This ensures that routes to the NAT gateway's subnet are propagated across all regions."

"When using Network Connectivity Center spokes, you can use export policies to control which routes are advertised from a spoke to the hub. An include policy specifies the exact prefixes to advertise."Reference: Google Cloud Private NAT Documentation, Network Connectivity Center Documentation - Spoke policies, VPC Network Documentation - Dynamic routing mode

The correct answer is B and C. You must create firewall rules for health checks and reserve a static IP address for the load balancer before creating the internal HTTP(S) load balancer.

The other options are not correct because:

Option A is not a prerequisite task. You can choose a region when you create the load balancer, but you do not need to do it beforehand.

Option D is not a prerequisite task. You can determine the subnet mask for a proxy-only subnet when you create the subnet, but you do not need to do it beforehand.

Option E is not related to the internal HTTP(S) load balancer. Serverless VPC Access is a feature that allows you to connect your serverless applications to your VPC network, but it is not required for the load balancer.

Direct Interconnect will be too expensive and also an overkill for this requirement. Managing multiple tunnels that too with packet loss consideration is complex also. Whereas partner interconnect fits the bill with providing required bandwidth but not super expensive also once setup not too complex too manage.

The correct answer is B. From the Cloud CLI, run gcloud compute --project_ID router get-status mycloudrouter --region REGION and review the results.

This command will show you the BGP session status, the advertised and learned routes, and the last error for each VLAN attachment. You can use this information to troubleshoot the asymmetric traffic flow and identify any issues with the BGP configuration or the Interconnect connections.

The other options are not correct because:

Option A will only show you the BGP session status, but not the advertised and learned routes or the last error for each VLAN attachment.

Option C will only show you the VPC Flow Logs, which are useful for monitoring and troubleshooting network performance and security issues within your VPC network, but not for your Interconnect connections.

Option D will only show you the basic information about the Cloud Router, such as its name, region, network, and BGP settings, but not the detailed status of each VLAN attachment.