Go to the command prompt and type IPCONFIG.
What is the ip address that you get ?
Now ping the Default gateway..If you get a reply from the Default gateway then ping 4.2.2.2 if there is a reply from 4.2.2.2 then ping google.com and if there is reply from google also then go to the TCP /ip setting and give a static DNS.
DNS1: your default gateway
DNS2 :4.2.2.2
If you don't get a reply from 4.2.2.2 if seems that there is a issue with the internet connection. Now since you have mentioned that your MAC is going online Assuming that you guys are connecting to the same network , there should be no issue with the network.
In the command prompt type:
NETSH WINSOCK RESET CATALOG then reboot the machine and try the steps again of pinging