before own config-files in /etc/dnsmasq.d get loaded, this folder have to be activated in /etc/dnsmasq.conf by removing the sharp (#) on beginning of the following line

conf-dir=/etc/dnsmasq.d

The Interface-config is separated in my setup to /etc/dnsmasq.d/interfaces.conf. In this file interfaces and their Settings are defined.

which Interfaces should respond to DHCP-Requests (binding)?

interface=lan0
interface=wlan1
#interface=tun0
interface=lxcbr0
interface=ap0

which interfaces send no DHCP-answer?

no-dhcp-interface=eth0
no-dhcp-interface=eth1

the settings for DHCP:

dhcp-range=lan0,192.168.0.100,192.168.0.150,255.255.255.0,48h
dhcp-option=lan0,3,192.168.0.10
dhcp-range=ap0,192.168.10.100,192.168.10.150,255.255.255.0,48h
dhcp-option=ap0,3,192.168.10.1
dhcp-range=wlan1,192.168.11.100,192.168.11.150,255.255.255.0,48h
dhcp-option=wlan1,3,192.168.11.1
dhcp-range=lxcbr0,10.0.3.100,10.0.3.150,255.255.255.0,48h
dhcp-option=lxcbr0,3,10.0.3.1

dhcp-range=interface,ip-range-start,ip-range-end,netmask,lease-time dhcp-option=interface,3,Default-Gateway

Per client dns setting:

Add set option to host between mac and ip (after name)

set:specialhosts

And set dns-servers for that name

 dhcp-option=tag:specialhosts,option:dns-server,8.8.8.8,8.8.4.4

https://serverfault.com/questions/509388/per-client-dns-servers-with-dnsmasq

DNSMASQ can answer a DHCP-Request from a specific MAC-address always with same IP-address. For that i have also created a separate config-file (/etc/dnsmasq.d/mac.conf).

an Entry for that looks like this:

dhcp-host=b8:27:eb:90:e6:06,raspberry,192.168.0.2,12h

MAC-Address of the Client, a name, the desired IP-Address and last param is the Lease-time (how long lasts the DHCP-answer ⇒ renew of IP needed)

on wifi i have the problem, that i have 2 WIFI-APs (with different IPv4-Subnet) running on R2 and on both the same MAC-addresses can send a query. here the entry can contain the interface:

dhcp-host=ap0,00:25:d3:f5:32:4b,media,192.168.10.11,12h
dhcp-host=wlan1,00:25:d3:f5:32:4b,media,192.168.11.11,12h

# service dnsmasq stop
Stopping DNS forwarder and DHCP server: dnsmasq.
# nano /var/lib/misc/dnsmasq.leases
# service dnsmasq start
Starting DNS forwarder and DHCP server: dnsmasq.

to allow answers for vpn and lxc network

https://serverfault.com/questions/844162/dnsmasq-ignores-queries-from-non-local-network