SSO Not Working When Visiting via Static DNS Entry

Hello,

We're getting ready to deploy SDP and one of the final items is setting up a user-friendly DNS entry (i.e. instead of http://servername/ we want http://helpdesk.domain.com/)

SSO works when visiting http://servername/ but it doesn't work when using the http://helpdesk.domain.com/ URL, we get prompted for credentials.

Here is the applicable login sequence via new URL:

2015-08-17 14:14:17: HttpSecurityService: C: GET /DynamicNotification.do

2015-08-17 14:14:17: HttpSecurityService: isProtected=true,token=true,passwordCredential=false,provider=true,isLogout=false,isAnonymous=false,connectionId=172.18.120.40:56508,authContexts.size=0

2015-08-17 14:14:17: HttpSecurityService: C: GET /DynamicNotification.do

2015-08-17 14:14:17: HttpSecurityService: isProtected=true,token=true,passwordCredential=false,provider=true,isLogout=false,isAnonymous=false,connectionId=172.18.120.40:56508,authContexts.size=1

Here is the applicable log for the http://servername/ URL:

2015-08-17 14:14:40: HttpSecurityService: C: GET /ntlmv2

2015-08-17 14:14:40: HttpSecurityService: isProtected=true,token=true,passwordCredential=false,provider=false,isLogout=false,isAnonymous=false,connectionId=172.18.120.51:53083,authContexts.size=1

2015-08-17 14:14:40: HttpSecurityService: domain\username successfully authenticated

2015-08-17 14:14:40: HttpSecurityService: C: GET /HomePage.do