Which of the following are system metadata for objects in S3? (choose 3 options)
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A. B. C. D. E.Answer: A, C, D.
AWS S3 bucket objects contain two kinds of metadata, system metadata and user-defined metadata.
System metadata:
Metadata such as object creation date is system controlled where only Amazon S3 can modify the value.
Other system metadata, such as the storage class configured for the object and whether the object has server-side encryption enabled, are examples of system metadata whose values you control.
If your bucket is configured as a website, sometimes you might want to redirect a page request to another page or an external URL.
In this case, a webpage is an object in your bucket.
Amazon S3 stores the page redirect value as system metadata whose value you control.
When you create objects, you can configure values of these system metadata items or update the values when you need to.
User-defined metadata:
When uploading an object, you can also assign metadata to the object.
You provide this optional information as a name-value (key-value) pair when you send a PUT or POST request to create the object.
When you upload objects using the REST API, the optional user-defined metadata names must begin with "x-amz-meta-" to distinguish them from other HTTP headers.
For more information on object metadata, refer to documentation here.
https://docs.aws.amazon.com/AmazonS3/latest/dev/UsingMetadata.html#object-metadataFor additional information:
https://docs.aws.amazon.com/AmazonS3/latest/API/RESTObjectPUT.htmlSystem metadata for objects in Amazon S3 are a set of predefined metadata that S3 uses to store information about the object. These metadata are set by S3 itself and cannot be modified by the user.
Out of the given options, the following are the system metadata for objects in S3:
A. x-amz-server-side-encryption: This metadata specifies whether the object is encrypted server-side using S3-managed encryption keys (SSE-S3), customer-provided encryption keys (SSE-C), or AWS Key Management Service (KMS) encryption keys (SSE-KMS). This metadata is automatically set by S3 when the object is uploaded with server-side encryption.
C. x-amz-version-id: This metadata is a unique identifier for a specific version of an object in a versioned bucket. When versioning is enabled for a bucket, each object version is assigned a unique version ID.
E. x-amz-meta-location: This metadata can be set by the user to provide additional information about the object's physical location, such as the data center or region where the object is stored.
The following options are not system metadata for objects in S3:
B. x-amz-meta-object-id: This metadata is not a system metadata but a user-defined metadata. It can be used to store a unique identifier for an object, such as a database ID.
D. Content-Length: This metadata specifies the size of the object in bytes and is not a system metadata.
Therefore, the correct answers are A, C, and E.