Why do AirVPN DNS servers hate the website usps.com so much?

[Oleg_NYC 0]

Why do AirVPN DNS servers hate the website usps.com so much? At first, I couldn’t figure out why I could load usps.com on my FreeBSD machine but not on my Android smartphone. Then I realized that, on FreeBSD, the DNS fallback mechanism configured in /etc/resolv.conf was causing a DNS leak: usps.com would load in Chromium because my ISP’s DNS servers were being used. I had to make sure that resolv.conf was automatically configured to use AirVPN DNS first and, from now on, to fall back to Cloudflare DNS or Google DNS instead of my ISP’s DNS. But I’m curious: why can’t AirVPN DNS resolve usps.com?