Your resolver broken.

opcode QUERY rcode NOERROR flags QR RD RA ;QUESTION alexa.com. IN A ;ANSWER alexa.com. 59 IN A 13.249.109.63 alexa.com. 59 IN A 13.249.109.113 alexa.com. 59 IN A 13.249.109.43

Ah. Probably my router's adblock.

I can resolve the host directly querying 1.1.1.1 or 8.8.8.8 resolvers.

Not broken so much as working as configured ;-)

Cool, makes sense. Here's a tool you can use to verify that it's not your system that's stopping the request https://toolbox.googleapps.com/apps/dig/

I actually verified by running dig locally, but thanks.

Disable your DNS adblocker?

Yes: https://news.ycombinator.com/item?id=29489793