SPSite.HostHeaderIsSiteName property
SharePoint 2013
Gets a Boolean value that specifies whether the host header is used instead of the server-relative path to uniquely identify the site collection.
Assembly: Microsoft.SharePoint (in Microsoft.SharePoint.dll)
Property value
Type: System.Booleantrue if the host header is used instead of the server relative path to uniquely identify the site collection; otherwise, false.