I don't know where you got that header; S3 returns Server: AmazonS3 and http://aws.amazon.com http://aws.amazon.com returns Server: Server. I would suspect a lo

I don't know where you got that header; S3 returns Server: AmazonS3 and http://aws.amazon.com http://aws.amazon.com returns Server: Server. I would suspect a lot of their backend services use custom HTTP servers, and maybe a small handful actually use apache. Moreover you'll be completely missing backend servers that have no public IP at all...