You are tasked with deploying a load balancer in Google Cloud that does not terminate sessions arriving from outside the VPC and that forwards…

The requirement is for a load balancer that accepts traffic from outside the VPC but does not terminate the session, instead forwarding it directly to internal backends. This describes a pass-through load balancer. The Google Cloud External Passthrough Network Load Balancer is a Layer 4, regional, pass-through load balancer. It is not a proxy; it forwards traffic to backends while preserving the client's source IP address. This behavior ensures the original session is not terminated by the load balancer, meeting the key requirement of the task.

(Assuming the following were the options)

A. Internal TCP/UDP Load Balancer: This load balancer is internal and cannot receive traffic originating from outside the VPC network.

B. Global External HTTPS Load Balancer: This is a proxy-based load balancer that terminates the client's HTTP/S session, which violates the stated requirement.

D. Internal HTTPS Load Balancer: This is incorrect for two reasons: it is internal-facing only, and it is a proxy that terminates sessions.

1. Google Cloud Documentation, "Choose a load balancer": The decision flowchart and summary table clearly distinguish between proxy and pass-through load balancers. For external, non-HTTP(S) traffic requiring a pass-through model, the guide directs users to the External Passthrough Network Load Balancer.

Source: Google Cloud, Load Balancing documentation, "Choose a load balancer", available at: https://cloud.google.com/load-balancing/docs/load-balancer-overview (Refer to the "Summary of Google Cloud load balancers" table).

2. Google Cloud Documentation, "External passthrough Network Load Balancer overview": This document explicitly states, "External passthrough Network Load Balancers are Layer 4 pass-through load balancers. These load balancers are not proxies. The load-balanced packets are received by the backend virtual machine (VM) instances with the packet's source and destination IP addresses...unchanged."

Source: Google Cloud, Load Balancing documentation, "External passthrough Network Load Balancer overview", available at: https://cloud.google.com/load-balancing/docs/network/network-lb-overview (Refer to the introductory paragraphs).