Upstream name servers are written to resolv.conf when 'dns=dnsmasq' and dnsmasq gets killed
When dnsmasq get killed, NM restarts it but writes upstream name servers to resolv.conf
# cat /etc/resolv.conf
# Generated by NetworkManager
nameserver 127.0.0.1
# killall dnsmasq
# cat /etc/resolv.conf
# Generated by NetworkManager
nameserver 192.168.122.1
nameserver 1.1.1.1
nameserver 2.2.2.1