Quelle: https://computingforgeeks.com/install-and-configure-dnsmasq-on-ubuntu/
sudo systemctl disable systemd-resolved
sudo systemctl stop systemd-resolved
ls -lh /etc/resolv.conf
sudo unlink /etc/resolv.conf
echo nameserver 8.8.8.8 | sudo tee /etc/resolv.conf
sudo apt update
sudo apt install dnsmasq
# Listen on this specific port
# Setting this to zero completely disables DNS function,
# leaving only DHCP and/or TFTP.
port=53
# Never forward plain names (without a dot or domain part)
domain-needed
# Never forward addresses in the non-routed address spaces.
bogus-priv
# Reihenfolge wie in /etc/resolv.conf
strict-order
# Add domain name to simple names in a hosts-file
expand-hosts
# Set the domain for dnsmasq. this is optional, but if it is set, it
# does the following things.
# 1) Allows DHCP hosts to have fully qualified domain names, as long
# as the domain part matches this setting.
# 2) Sets the "domain" DHCP option thereby potentially setting the
# domain of all systems configured by DHCP
# 3) Provides the domain part for "expand-hosts"
domain=btin.lan
# Set Listen address
listen-address=192.168.100.10 # Set to Server IP for network responses
sudo systemctl restart dnsmasq
192.168.100.101 web1.lan
192.168.100.101 web2.lan
sudo systemctl restart dnsmasq
dhcp-range=192.168.100.20,192.168.100.30,1h
dhcp-option=option:router,192.168.100.1
dhcp-option=option:ntp-server,192.168.100.1
dhcp-option=option:dns-server,192.168.100.10
dhcp-option=option:netmask,255.255.255.0
sudo systemctl restart dnsmasq