As per my last discussion with Bucking_Horn, supposedly the ff. steps below should address this problem:
"Edit file /etc/resolvconf.conf and comment out the last line which should read:
unbound_conf=/etc/unbound/unbound.conf.d/resolvconf_resolvers.conf
Delete the unwanted unbound configuration file:
sudo rm /etc/unbound/unbound.conf.d/resolvconf_resolvers.conf
Restart unbound:
sudo service unbound restart"
It still works, however...
Actual Behaviour:
Every time I restart the RPI or for some instance, it returns SERVFAIL as I check on my query log. I do the same steps above, and it fixes it. But I have to do it every now and then. It seems an unusual behavior to me.
That last unbound_conf= line should be commented out with a hash # like below or else every reboot, the resolvconf_resolvers.conf file will be restored:
pi@ph5b:~ $ sudo nano /etc/resolvconf.conf
# Configuration for resolvconf(8)
# See resolvconf.conf(5) for details
resolv_conf=/etc/resolv.conf
# If you run a local name server, you should uncomment the below line and
# configure your subscribers configuration files below.
#name_servers=127.0.0.1
# Mirror the Debian package defaults for the below resolvers
# so that resolvconf integrates seemlessly.
dnsmasq_resolv=/var/run/dnsmasq/resolv.conf
pdnsd_conf=/etc/pdnsd.conf
#unbound_conf=/etc/unbound/unbound.conf.d/resolvconf_resolvers.conf