DHCP network

hello, My cousin just came from Canada and brought her MacBook. It's has Mac OS X v10.5.5. I'm unfamiliar with it. I live in Pakistan and almost every one uses Windows based PCs. Here we have a internet connection that we are DHCP Client. When we plug the wire into windows based PC it connects automatically and an IP is assigned automatically. But when I plug the wire into MacBook after spoofing the MAC Address (registered in DHCP server) it don't assign that IP and internet won't work. Please suggest me how can I resolve this issue.

Thanks

Why do you have to spoof the MAC address? Is the router locked only to your PC's MAC address?

If the Mac is configured for DHCP it should obtain an IP automatically.

If you have just a cable/dsl modem, you might have to power cycle (with the PC disconnected) it to get it to forget the PC's MAC ID and then plug in the MacBook.

you need to hard reset the cable modem. Currently the router is only registering the PC not the mac. The mac address is locked into the router. You just have to hard reset it. Call your ISP