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We have SSRS (SQL Server Report Service) running on an Amazon EC2 instance.

It had been named using an A record. Recently we changed it to a CNAME referencing the EC2 public DNS name. (Why: This way, 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

  • Before: It would simply deploy.
  • After: There is a login prompt asking for a username and password for 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.

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up vote 0 down vote accepted

Because the machines probably aren't members of your Windows domain so the credentials can't simply be passed across like it could when the machine was a member of your domain.

Or was it working when you had the public name setup as a A record but that changed when you switched it to a CNAME record?

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Yes, it was working differently when was set up as an A record. The login prompts started appearing when we switched to a CNAME record. Some client (like VS and IE) prompt now, but only some clients and in some situations. I don't understand why, or how to change that. – Greg Hendershott Aug 2 '11 at 11:57
Strange, the DNS record type shouldn't matter. All the application gets back is an IP address to connect to. I'd double check the IIS settings to make sure that things didn't get screwed up in there somehow. – mrdenny Aug 2 '11 at 23:28
were you always using a FQDN to deploy? I wonder if it is an issue with automatic login in IE – Jason Horner Aug 17 '11 at 6:16

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