Gist
Testing DNS and services on localhost
Local DNS and http://localhost testing guide: add loopback IP aliases, update /etc/hosts for multiple local domains, and run Next.js on custom host/IPs to test multi-domain setups on one machine.
Creating more loopback endpoints locally
sudo ifconfig lo0 alias 127.0.0.2 up
Update /etc/hosts file to point the domain to the new IP
##
# Host Database
#
# localhost is used to configure the loopback interface
# when the system is booting. Do not change this entry.
##
127.0.0.1 localhost
255.255.255.255 broadcasthost
::1 localhost
127.0.0.2 app.local
127.0.0.3 host.local
Next JS command to run on above port
npx next dev -H 127.0.0.2 -p 3001