dns check outside dns before local
 

there is a problem faceing me i can't understand it
i have a Small network (fedora+ xp)
a have the dns in my server
this server is connected to the INTERNET by adsl modem
now the problem is
when i ping the server by host name it be so slow to give me the replay
but the time of the replay being good and fast
second when i do ssh by ip
he do it fast and ask me for password fast
but it take a long time to check the password
all these cases happened when i disconnect from the INTERNET (unplug network cable from the external interface
when i put the cable of the modem
i every thing being OK ssh is fast and ping is fast
i try to dig the server
i found that it go to the external dns to get the request and come again to the local
i don't understand why this happend
why it go to outside dns and not look to the local dns first
can anyone help me please

Look into /etc/resolv.conf. It's a list of DNSes. They're asked in the order from this file. If you local DNS (using local IP) is not first on the list, make it first.