Redirect all traffic on a wildcard domain to an IP address using Dnsmasq on Mac

install-dnsmasq

# install dnsmasq with Brew
brew install dnsmasq

# follow instructions on how to create a config file and startup entries
# copy example config to live config file
cp /usr/local/opt/dnsmasq/dnsmasq.conf.example /usr/local/etc/dnsmasq.conf

# install startup script
sudo cp -fv /usr/local/opt/dnsmasq/*.plist /Library/LaunchDaemons

# edit the configuration
vim /usr/local/etc/dnsmasq.conf

# listen on localhost
listen-address=127.0.0.1

# redirect all traffic to *.example.com to 127.0.0.1
address=/example.com/127.0.0.1

# make your computer use dnsmasq for DNS in System Preferences -> Advanced
# add 127.0.0.1 as the first DNS server entry for your connection
# /etc/resolv.conf is autogenerated on Mac and will be overwritten if you edit it

# you'll need to restart dnsmasq each time you make changes to the configuration file

# start dnsmasq
sudo launchctl load /Library/LaunchDaemons/homebrew.mxcl.dnsmasq.plist

# stop dnsmasq
sudo launchctl unload /Library/LaunchDaemons/homebrew.mxcl.dnsmasq.plist