Exam AWS-SysOps topic 1 question 739 discussion

D is the answer. DependsOn is an attribute not a resource and AWS::CloudFormation::Init is used to include metadata on an EC2 for the cfn-init helper script. Although there are other options for this particular case, if we relate only to the questions the answer can be found here: https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-waitcondition.html "You can use the wait condition and wait condition handle to make AWS CloudFormation pause the creation of a stack and wait for a signal before it continues to create the stack. For example, you might want to download and configure applications on an Amazon EC2 instance before considering the creation of that Amazon EC2 instance complete."

D: The WaitCondition CloudFormation "resource" might look similar to the DependsOn attribute, but they’re actually different. DependsOn controls the order in which your CloudFormation resources are created, i.e., creation of a specific resource follows another. DependsOn doesn’t wait for success or failure signals from AWS resources before moving forward. While, on the other hand, WaitCondition waits for success signals from your AWS resources and resumes the execution of the CloudFormation template

The WaitCondition resource in CloudFormation allows you to delay the creation of dependent resources until a specific condition is met. In this scenario, you can use a WaitCondition to delay the creation of the Elastic Load Balancer until the initialization script on the EC2 instances has been successfully executed.

D is the answer

I'll go with D

C is correct. WaitforCondition is recommended for waiting external resource. Dependson is not used during a creating process. we need here cfn-signal in init()

C is correct. WaitforCondition is recommended for waiting external resource. Dependson is not used during a creating process. we need here cfn-signal in init()

Correct Answer: D

D is the answer At first I would say " depends ON" would be enough but question states that "The creation of each EC2 instance will not be considered complete until an initialization script has been run successfully on the EC2 instance" and based on that, I would then choose D

D as fyzzzz mentioned DependsOn is an attribute not a resource , as per link below depend on basically needed for VPC-gateway attachment "when a resource like ec2 instance is depending on a gateway to be created" https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-attribute-dependson.html#gatewayattachment

D. WaitCondition Seem correct

I'll go with D

B With the DependsOn attribute you can specify that the creation of a specific resource follows another. When you add a DependsOn attribute to a resource, that resource is created only after the creation of the resource specified in the DependsOn attribute. https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-attribute-dependson.html

D should be the answer as the key word here is that there is a custom script and need to get it finished before create ELB.

D is the answer. DependsOn is an attribute not a resource and AWS::CloudFormation::Init is used to include metadata on an EC2 for the cfn-init helper script. Although there are other options for this particular case, if we relate only to the questions the answer can be found here:

D is correct

D: With full exp and example too: https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-properties-waitcondition.html