shell:$ nslookup -timeout=2 -retry=1 'readthedocs.io'
Server:		1.1.1.1
Address:	1.1.1.1#53

Non-authoritative answer:
Name:	readthedocs.io
Address: 104.16.253.120
Name:	readthedocs.io
Address: 104.16.254.120
Name:	readthedocs.io
Address: 2606:4700::6810:fe78
Name:	readthedocs.io
Address: 2606:4700::6810:fd78