When you attempt to navigate to delta.com through Symantec Web Gateway (SWG) appliance in Proxy mode or INLINE+Proxy mode, you receive a message indicating a DNS error. When you bypass SWG appliance and navigate directly, you receive the site without error.

Within the Internet Explorer client browser, an error similar to the following is displayed:

"Symantec Web Gateway

The requested URL could not be retrieved

While trying to retrieve the URL: http://prd1a12.delta.com:17023/shared/core/alert/index.jsp

The following error was encountered: 

           Unable to determine IP address from host name for prd1a12.delta.com

The DNS server returned:

           Name error: The domain name does not exist.

This means that:

            The proxy server was not able to resolve the hostname presented in the URL.
            Check if the address is correct."

The site delta.com issues a redirect to SWG appliance contains a hostname with no globally published 'A' record in DNS.

Contact delta.com for assistance with this issue.

While working with delta for assistance, bypass the SWG appliance in proxy mode. To do so, issue an exception for the delta.com website in a proxy.pac file to each of the client browsers.