network services may be slow (sendmail, CUPS etc) because default nameserver for the router always takes long time to resolve. To overcome this problem you have to load caching-nameserver, so does not have to do resolution every time.

'''yum install caching-nameserver '''

in '''system-config-network''' change DNS to 127.0.0.1

make sure to restart named:

'''service named restart '''

'''chkconfig named on'''

Just in case restart slow services (eg sendmail & cups)