Challenge 2: Why Reverse-Proxy a Single Node.js Instance — Solution Walkthrough

An accurate answer:

Load balancing is only one reason to put a reverse proxy in front of
an application — not the only one. Per this chapter's own warning box,
a reverse proxy in front of a single backend is genuinely common,
usually for reasons that have nothing to do with distributing traffic
across multiple instances:

  - TLS termination: Nginx can handle the HTTPS encryption/decryption
    layer itself, so the Node.js application only ever has to speak
    plain HTTP internally, never handling certificates or TLS
    directly.
  - Caching: Nginx can cache responses for content that doesn't change
    on every request, reducing load on the Node.js application without
    the application needing any caching logic of its own.
  - Protocol/interface translation: Nginx presents a clean, standard
    HTTPS interface to the outside world regardless of what the
    backend application actually speaks internally.

None of these benefits require a second backend instance to exist —
they're valuable with exactly one Node.js process running behind the
proxy.

WHY THIS WORKS AS AN ANSWER
------------------------------
This exercise checks that the chapter's own central warning-box point
— reverse proxying is not synonymous with load balancing — is
understood well enough to name concrete alternative reasons for a
single-backend scenario, rather than defaulting to "load balancing" as
the only justification for using a reverse proxy at all.