network administration

wen i am accessing my own company web site,i cant reach, like wen i am putting www….
nt getting,bt i cn reach thru the web site..64…..
bt rest of the world can reach..so i thnk our local DNS server is nt set up correctly..
so how to relove this problem?plz give suggestion tell me in details step by step..
wat to do?
how to configure local DNS server to resolve this problem?