Exam AWS Certified Solutions Architect - Professional topic 1 question 221 discussion

C. No, you cannot add an IfExists condition at the end of a Null condition.

C. No, you cannot add an IfExists condition at the end of a Null condition. In IAM policies, conditions allow you to specify additional constraints for when a policy statement should be evaluated. However, there is no direct support for an "IfExists" condition in IAM policies. The available condition operators in IAM policies include Null, StringEquals, NumericEquals, Bool, and so on, but "IfExists" is not one of them. The Null condition checks if a specific key exists in the request context but doesn't evaluate the value of that key. It cannot be combined with an IfExists condition as there is no IfExists condition in IAM policies.

Within an IAM policy, IfExists can be added to the end of any condition operator except the Null condition. It can be used to indicate that conditional comparison needs to happen if the policy key is present in the context of a request; otherwise, it can be ignored. http://docs.aws.amazon.com/IAM/latest/UserGuide/reference_policies_elements.html C is correct

C. No, you cannot add an IfExists condition at the end of a Null condition.

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C You can add IfExists to the end of any condition operator name except the Null condition—for example, StringLikeIfExists. You do this to say "If the policy key is present in the context of the request, process the key as specified in the policy. If the key is not present, evaluate the condition element as true." Other condition elements in the statement can still result in a nonmatch, but not a missing key when checked with ...IfExists.

https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_policies_elements_condition_operators.html#Conditions_IfExists