DONE

It sounds like your router needs to port-forward traffic from outside the LAN to the apache server inside the LAN. If the router is a Linux/iptables based host, you will need to explore the router's firewall configuration and add the port-forward and mangle rules. Do you presently have other hosts running services that are accessible from the WAN side of the router? If so, the iptables rules that support those should make an identifiable model for the required modifications. What, exactly, are you doing to test accessibility of the apache server from the WAN side of the router?
Rather than using a nameserver for name resolution inside your LAN, it is probably simpler to just add the server to /etc/hosts.
Sorry I can't be more specific, but there are too many unknowns at this point.
--- rod.

Does my reverse DNS have something to do with it? coz i think im not able to configure/done it correctly. how will i check either if my reverse dns lookup works fine?

If this is a home DSL/cable network connection, it is not unusual to have no IP name. Identifying the server by dotted-decimal IP should satisfy any ordinary web browser.
--- rod.

DONE