you are right. installation could not locate dnsutils because I have removed it when pihole uninstallattion process asked me.
could not install dnsutils because I have removed all the packages from source.list.
I have tried to re-add sources but does not work.
always getting
sudo apt-get install dnsutils
Reading package lists... Done
Building dependency tree
Reading state information... Done
Package dnsutils is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
However the following packages replace it:
bind9-host
E: Package 'dnsutils' has no installation candidate