You have an application that receives SSL-encrypted TCP traffic on port 443. Clients for this application are located all over the world. You want to minimize latency for the clients. Which load balancing option should you use?

The requirement is to serve SSL-encrypted TCP traffic to a global user base with minimal latency. The External SSL Proxy Load Balancer is the ideal solution. It is a global service that terminates user SSL/TLS connections at a Google Cloud network point of presence (PoP) closest to the client. This termination at the edge significantly reduces latency, especially for the initial SSL handshake. The load balancer then communicates with the backend instances, typically over an unencrypted channel within Google's network. This design is specifically for non-HTTP(S) SSL traffic, which perfectly matches the "SSL-encrypted TCP" description.

A. HTTPS Load Balancer: This is a global load balancer, but it is designed specifically for HTTP(S) traffic (Layer 7). The question specifies generic "SSL-encrypted TCP," which is not necessarily HTTP.
B. Network Load Balancer: This is a regional, pass-through load balancer (Layer 4). It does not terminate the SSL connection and cannot leverage Google's global network to reduce latency for worldwide clients.
D. Internal TCP/UDP Load Balancer: This load balancer is for internal traffic within a Google Cloud VPC. It cannot be used to serve traffic from external clients on the public internet.

1. Google Cloud Documentation

"Choose a load balancer": The decision tree on this page guides users to the correct load balancer. For "Global" traffic from the "Internet" that is "Non-HTTP(S) traffic

" the recommended solution is the "External SSL Proxy Load Balancer."

Source: Google Cloud Documentation

"Cloud Load Balancing overview"

section "Summary of Google Cloud load balancers".

2. Google Cloud Documentation

"External SSL Proxy Load Balancing overview": "External SSL Proxy Load Balancing is a reverse proxy load balancer that distributes SSL traffic coming from the internet to virtual machine (VM) instances in your Google Cloud VPC network. ... When you want to load balance non-HTTP(S) traffic for a global audience

you should use an SSL Proxy Load Balancer."

Source: Google Cloud Documentation

"External SSL Proxy Load Balancing overview".

3. Google Cloud Documentation

"External SSL Proxy Load Balancing overview"

section "Benefits": "SSL proxy load balancers terminate user TLS sessions at the load balancing layer. ... Terminating TLS sessions at the load balancer enables the load balancer to route connections to backends more efficiently." This termination at the edge is the key to reducing latency.

Source: Google Cloud Documentation

"External SSL Proxy Load Balancing overview"

section "Benefits".

4. Google Cloud Documentation

"External TCP/UDP Network Load Balancing overview": "External TCP/UDP Network Load Balancing is a regional

pass-through load balancer. ... Because the load balancer is a pass-through load balancer

your backends terminate the client TCP connection or UDP packets." This confirms it is regional and does not terminate SSL

making it unsuitable for this scenario.

Source: Google Cloud Documentation

"External TCP/UDP Network Load Balancing overview".