Is it true that Ubuntu doesn't have DNS cache by default and what options I have to enable it ? Is bind9 option that can enable caching of DNS ?
Ubuntu Desktop have dnsmasq-base package built-in in NetworkManager, but with the dns cache function disabled, you can check in your logs:
zgrep dnsmasq /var/log/syslog* | grep disabled .... dnsmasq: started, version 2.68 cache disabled ....
you can install dnsmasq if you are using Ubuntu Server and this have cache enabled by default.
If you are in Ubuntu Desktop, you can enable cache in dnsmasq-base/network-manager with this:
add one file in
sudo vim /etc/NetworkManager/dnsmasq.d/cache
add this line:
and after this in command line:
sudo restart network-manager
try to NOT install dnsmasq in Ubuntu Desktop, enable caching with dnsmasq-base. If you are in Ubuntu Server, install dnsmasq if is not already installed.