MacBook Air will not connect to the internet

I am trying to assist my wife with her Macbook air (MbA), it will no longer connect to the "internet". BACKGROUND: I am running Century Link DSL Modem, with a Belkin Wireless router. I have about 10 different nodes on my home network, PC, Apple and Droid devices. All of which have no issues with access to the internet. My wife's MbA however will not access the web, it does however connect to my network and get a DHCP assigned IPv4 Address from my network. I am able to go to addresses and inside my network and serve up http such as my router's web page. WHAT I HAVE TRYIED: I have flushed/removed all previously connected wireless networks on the MbA and turned off wireless on the device then shutdown and restarted it and reconnected to my SSID (wireless network) = no joy, didn't work. I have rebooted all of my network equipment = no joy, didn't work. I have changed the DNS to an address outside my network = no joy, didn't work. I don't know alot about Mac/apple product, they seem simple and straight forward, and I have been a cisco routrer/switch jockey for about the last 7 years of my carreer.... this one stumps me. Any ideas? Firewall configuration, is there a "intranet" only box checked somewhere?

PS... I may have miss spelled my words, human communication matters, spelling is over rated. 🙂