If you find the named process on your Ubuntu/Linux based server taking up a high amount of (e.g. 99%) CPU time, then check if the
/var/cache/bind directory has the correct permissions.
If you run
ll -d /var/cache/bind and find that only the root user has write permissions to the directory, i.e. it looks like the following:
drwxr-xr-x 2 root root 4.0K Apr 14 15:29 /var/cache/bind
Switch to the root user and change the group to bind, and give it write permissions, by running the following:
chown root:bind /var/cache/bind chmod g+w /var/cache/bind
Then you will just need to restart bind9 by running the following:
service bind9 restart
Now it should be behaving better.