A user has created a VPC with public and private subnets using the VPC Wizard. The VPC has CIDR 20.0.0.0/16. The
private subnet uses CIDR 20.0.0.0/24. Which of the below mentioned entries are required in the main route table to allow
the instances in VPC to communicate with each other?

A.
Destination : 20.0.0.0/24 and Target : VPC
B.
Destination : 20.0.0.0/16 and Target : ALL
C.
Destination : 20.0.0.0/0 and Target : ALL
D.
Destination : 20.0.0.0/16 and Target : Local
Explanation:
A user can create a subnet with VPC and launch instances inside that subnet. If the user has created a public private
subnet, the instances in the public subnet can receive inbound traffic directly from the Internet, whereas the instances in
the private subnet cannot. If these subnets are created with Wizard, AWS will create two route tables and attach to the
subnets. The main route table will have the entry “Destination: 20.0.0.0/24 and Target: Local”, which allows all instances
in the VPC to communicate with each other.
Highlighted wrong answer: The explanation states “Destination: 20.0.0.0/24 and Target: Local” so it should be D. Crossed checked with my route tables as well.
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I agree, it should be D. I believe that the term of “main route table” points to the route table of the VPC.
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The explanation is correct. It Should be D:
The main route table will have the entry “Destination: 20.0.0.0/24 and Target: Local”, which allows all instances
in the VPC to communicate with each other
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D
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http://docs.aws.amazon.com/AmazonVPC/latest/UserGuide/VPC_Scenario2.html
Main Route Table
The first entry is the default entry for local routing in the VPC; this entry enables the instances in the VPC to communicate with each other.
Destination Target
VPC CIDR local
So answer for this questions is Destination : 20.0.0.0/16 and Target : Local
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No answer is right.
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Sorry ,D is right.
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D
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D
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Answer is D
Verified using aws default route table for VPC
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Correct answer is D.
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D
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D
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