爲什麼每次通話都必須更改CallerReference？

Question

我有這個Python + boto3。此代碼運行正常，並創建一個名爲test的託管區域。然而，當我用一個新名稱test2再次運行相同的代碼塊時，我還必須將CallerReference更改爲一些唯一值，在下面的代碼中它將從awsbuilder5到awsbuilder6等。 如果我不這樣做是，我得到這個錯誤：

An error occurred (HostedZoneAlreadyExists) when calling the CreateHostedZone operation: A hosted zone has already been created with the specified caller reference.

代碼是在這裏：

response = client.create_hosted_zone (
    Name = 'test', 
    VPC={ 
    'VPCRegion': 'us-east-1', 
    'VPCId': 'vpc-958122f0' 
    }, 
    CallerReference='awsbuilder5', 
    HostedZoneConfig={ 
    'Comment': 'Test', 
    } 
) 

Answer 1

從文檔，一個CallerReference：

A unique string that identifies the request and that allows failed create-hosted-zone requests to be retried without the risk of executing the operation twice. You must use a unique CallerReference string every time you create a hosted zone.

http://docs.aws.amazon.com/cli/latest/reference/route53/create-hosted-zone.html