dnsmasq and not dhcpcd

interfaces.ap

# interfaces(5) file used by ifup(8) and ifdown(8)

# Please note that this file is written to be used with dhcpcd
# For static IP, consult /etc/dhcpcd.conf and 'man dhcpcd.conf'

# Include files from /etc/network/interfaces.d:
# source-directory /etc/network/interfaces.d

# I dunno what's the purpose of these settings anymore
#auto br0
#iface br0 inet manual
#bridge_ports eth0 wlan0

# if rpi's eth0 is wired to a working router
# it will set eth0 ip address and wlan0 clients
# will have internet connectivity
## auto eth0
## iface eth0 inet dhcp

# By hardcoding a static ip address here
# `ps -ef` no longer shows 'dhcpcd' process
# which just waste CPU cycles and clarified
# the fact that `dnsmasq` is our one and true
# dhcp server of wlan0 clients
## allow-hotplug wlan0
## iface wlan0 inet static
## address 10.3.141.1
## netmask 255.255.255.0
## gateway 10.3.141.1

# For AP to work in RPI0W, /etc/network/interfaces should be empty
# and then, `ps -ef | grep dhcpd` must be running
# 
# This is not exactly the same with RPI3B, perhaps because 
# due to RPI0W's ethernet being a USB-attached?