Configuring OS X (10.x) to connect to the Comcast High-Speed Internet Service

Go to Apple Menu > System Preferences...

From System Preferences window, click on Network icon.

On the Show Menu, select Built-in Ethernet

Go to TCP/IP tab, and from the Configure IPv4 menu select Using DHCP. Click on Apply Now.

Now your computer should obtain an IP Address and all other parameters from the Comcast DHCP server.
You should be able to connect to the Internet now. But if you have any problem connecting to Internet, please proceed further.

Select the PPPoE tab, and make sure that Connect using PPPoE is NOT selected.

Select the Proxies tab, and make sure that none of the proxies are selected. Click on Apply Now.

Now your Internet settings are configured correctly and you should be able to connect to Comcast High-Speed Internet Service.

Enjoy!!!