We have SSRS (SQL Server Report Service) running on an Amazon EC2 instance.
It had been named report.foo.com using an A record. Recently we changed it to a CNAME referencing the EC2 public DNS name. (Why: This way, report.foo.com resolves to the EC2 public IP address outside EC2, but to the private IP address inside EC2. As you want, for security groups and data transfer charges.)
All is working well, except certain Microsoft web clients started to behave differently.
Example: Deploying a report from Visual Studio to https://report.foo.com/reportserver.
- Before: It would simply deploy.
- After: There is a login prompt asking for a username and password for https://report.foo.com/reportserver. If I supply valid credentials, it does work. But I'm puzzled why it's prompting at all, vs. before?
A similar example is links in Excel spreadsheets -- there's a prompt now that didn't exist before.