If you installed webalizer via MacPorts in your Mac OS X you must know that it comes without dns support. That’s why you’re getting those

Warning: Invalid keyword 'DNSCache' (webalizer.conf)
Warning: Invalid keyword 'DNSChildren' (webalizer.conf)
Warning: Invalid keyword 'DNSCache' (webalizer.conf)
Warning: Invalid keyword 'DNSChildren' (webalizer.conf)

To enable it , uninstall webalizer

sudo port -d uninstall webalizer

Edit the Portfile for webalizer

vi /opt/local/var/macports/sources/rsync.macports.org/release/ports/www/webalizer/Portfile

to add an

  --enable-dns \

(note the ending backslash “") in the configure.args section just before of

 --with-png=${prefix}/lib

now you have to install BerkeleyDB (in case it is not already installed)

sudo port -d install db47

then execute the port clean and port install and you should get a working dns enabled webalizer

sudo port -d clean webalizer
sudo port -d install webalizer

Hope it helps