Exchange connections not working DNS failing

Hello,

We are having issues with Outlook connections to Exchange. I am unable to resolve the DNS server entries externally or internally on our network to the Exchange servers listed in our account profile in Outlook. I can use nslookup to 75.75.75.75 or other public DNS, and it doesn't resolve to an address.

Our Mailbox server autoconfigured in Outlook is this:  W14MCLBCH2.W14D.comcast.net

(does not ping or resolve)

In OWA, which does work, it shows this server: W14MBX-CH2-D1.W14D.comcast.net

(does not ping or resolve)

I called Comcast business support, the rep told me I can only use Outlook proviced from the Comcast portal, and without that she cannot help me.  We have Office 2013 installed, which already has Outlook.  She also told me our server is this: 

w14pod-ch2-d.comcast.net

Which of course, doesn't ping or resolve.  

Wemail works, calls to comcast don't help, any help here is appreciated.  I really need to deal with a higher level support tech that understands what DNS is and Exchange basics.  Thanks for any help.

Greg