I am running dnsmasq (Version: 2.80-1.1ubuntu1.5) on Ubuntu-20.04.04, the network interface is being managed by Netplan rendered inuse is networkd.

The DNSMasq forwards requests to the upstream nameserver IP as defined for the resolution.No issues till now. But when I change nameserver IP and check the status of dnsmasq, it still shows request being forwarded to old nameserver IP. I even tested after restarting the DNSmasq service and machine, but the issue still persists.

Any help on this is highly appreciated.

Thanks in advance.



root@myserver:~# cat /etc/netplan/00-installer-config.yaml | grep -A3 "nameservers"

nameservers:
addresses:
- 10.0.3.2
- 8.8.4.4

root@myserver:~# systemctl status dnsmasq | grep -i nameserver
Sep 06 10:43:40 myserver dnsmasq[1318]: using nameserver 10.0.3.2#53
root@myserver:~# vi /etc/netplan/00-installer-config.yaml
root@myserver:~# netplan apply
root@myserver:~# cat /etc/netplan/00-installer-config.yaml | grep -A3 "nameservers"

nameservers:
addresses:
- 8.8.8.8
- 8.8.4.4

root@myserver:~# systemctl status dnsmasq | grep -i nameserver
Sep 06 10:43:40 myserver dnsmasq[1318]: using nameserver 10.0.3.2#53 <-------- OLD UP STREAM IP IN USE


+++Netplan config+++
root@myserver:~# cat /etc/netplan/00-installer-config.yaml
network:
version: 2
renderer: networkd
ethernets:
eth0:
addresses:
- 10.45.3.25/24
gateway4: 10.45.3.1
nameservers:
addresses:
- 8.8.8.8
- 8.8.4.4
root@myserver:~#


++++DNSMasq config+++
root@myserver:~# cat /etc/dnsmasq.conf | grep -v '#' |uniq
resolv-file=/etc/resolv.dnsmasq
listen-address=127.0.0.1,172.17.0.1
cache-size=1000
root@myserver:~#

There is no "Magic Link" between dnsmasq and, well, really anything else. Dnsmasq picks up the contents of resolv.conf at startup, or when triggered to update. (See man pages and how-to documents.)
When you change the addresses, do something like restart dnsmasq to pick up the changes.

what is in /etc/resolv.dnsmasq? That is supplanting /etc/resolv.conf and the input of netplan.