Consider `db` resolves to multiple A records:

  db.   IN   A    100.64.123.1   # prod-db-1.
  db.   IN   A    100.64.123.2   # prod-db-2.
  db.   IN   A    100.64.123.3   # prod-db-3.

This is good for service discovery—e.g., you can configure something like RabbitMQ to discover cluster members from an A record—and it's nice for browsers, which will pick one host at random when connecting, which effectively is load balancing.

In a usual setup, the problem is that if a host goes down, clients will still try to reach it because it's still in the DNS record; but with Tailscale, the "DNS" is generated by the local Tailscale daemon on the fly, so you get a live view, and if this was implemented, it would be possible to only return available servers for tag queries.