Exam AWS Certified DevOps Engineer - Professional DOP-C02 topic 1 question 89 discussion

B. Explanation: When using the S3 PutObject operation, you can include the MD5 checksum of the object in the Content-MD5 parameter of the request. Amazon S3 will calculate the MD5 checksum of the object and compare it to the provided checksum. If the checksums do not match, Amazon S3 will return an error response, indicating that the data integrity check failed. This way, you can ensure that the data was successfully copied to Amazon S3 without corruption. D. Explanation: When you use the S3 PutObject operation, it returns an ETag in the response, which is the MD5 checksum of the object that was stored in Amazon S3. After performing the upload, you can check the returned ETag against the MD5 checksum you have locally calculated. If they match, it means the data was transferred successfully without corruption. If they don't match, it indicates a data integrity issue, and you can take appropriate actions.

B: the content-MD5 header is used to provide a base64encoded 128-bit MD5 digest of the object data when included in a PutObject request, S3 checks the provided MD5 against what it calculates during upload If the checksums dont match, the request fails with an error (like http 4xx) this will ensure data was not corrupted during upload D: for single part uploads, the ETag returned by S3 is usually the MD5 checksum of the object. by calculating the MD5 of the local file and comparing it to the returned ETag, the script can verify integrity

If the object was created by a PutObject, PostObject, or Copy operation, or via the AWS Management Console, and the object is either plain text or encrypted with server-side encryption using the Amazon S3 managed key ( SSE-S3), the object's ETag is the MD5 digest of the object data.

B and D are correct: <verify whether the data was successfully copied to Amazon S3> means we need to check <operation call’s return status> code. <use MD5 checksums to verify data integrity> means we need to check ETag A: no mention of ETag C and E: no mention of ETag or return status code

BD refer this link: https://docs.aws.amazon.com/AmazonS3/latest/userguide/checking-object-integrity.html

BD are correct