company site is not getting acessed in dhcp network

I m not able to acess our company website in our dhcp networkIt gives error “Site Under Construction”.I m not able to find it out its a DNS Problem or what else.

if i acess site from machine not connected to my network it works and also if i ping site in CMD give reply from Site IP Address but if acess from DHCP network it give page under construction and if pinged give reply from DNS Address mand DNS server Address not website address.

Also let me tell our webserver is not located here it is out of india? Pls help

How do i resolve this??