Exam AWS Certified Solutions Architect - Associate SAA-C03 topic 1 question 296 discussion

10.0.1.0/32 and 192.168.1.0/32 are too small for VPC, and /32 network is only 1 host 192.168.0.0/24 is overlapping with existing VPC

• Option A (10.0.1.0/32) is invalid - a /32 CIDR prefix is a host route, not a VPC range. • Option B (192.168.0.0/24) overlaps the development VPC and so cannot be used. • Option C (192.168.1.0/32) is invalid - a /32 CIDR prefix is a host route, not a VPC range. • Option D (10.0.1.0/24) satisfies the non-overlapping CIDR requirement but is a larger block than needed. Since only two VPCs need to be peered, a /24 block provides more addresses than necessary.

In an Amazon VPC, the first four and the last IP address in each subnet are reserved for specific purposes, and they cannot be used for customer instances. Here's how the reserved addresses are typically allocated: Network Address (First IP): The first IP address (all zeros in the host portion) in a subnet is reserved as the network address. For example, if you have a subnet with a CIDR notation of 10.0.0.0/24, the network address would be 10.0.0.0. VPC Router (Second IP): The second IP address in the subnet is reserved for the VPC router. DNS Server (Third IP): The third IP address is reserved for the DNS server. Reserved for Future Use (Fourth IP): The fourth IP address is reserved for future use. Customer Instances (Fifth to Second-to-Last IP): The IP addresses from the fifth to the second-to-last IP address in the subnet are available for customer instances. Broadcast Address (Last IP): The last IP address (all ones in the host portion) in a subnet is reserved as the broadcast address, even though AWS does not support broadcast.

10.0.0.0 - 10.255.255.255 (10/8 prefix): Example CIDR block: 10.0.0.0/16 172.16.0.0 - 172.31.255.255 (172.16/12 prefix): Example CIDR block: 172.31.0.0/16 192.168.0.0 - 192.168.255.255 (192.168/16 prefix): Example CIDR block: 192.168.0.0/20 Given that the development VPC already uses 192.168.0.0/24, we need to choose a non-overlapping CIDR block. The smallest valid CIDR block that meets the requirements is 192.168.1.0/24 (Option C).

A and C are host IP addresses. B is not possible because it's using the same subnet for the other team/department. We are left with D, which is the right answer.

10.0.1.0/32 and 192.168.1.0/32 are too small for VPC, and /32 network is only 1 host 192.168.0.0/24 is overlapping with existing VPC

Definitely D. The only valid VPC CIDR block that does not overlap with the development VPC CIDR block among the options. The other 2 CIDR block options are too small.

D is correct.

D is the only correct answer

only one valid with no overlap

A process by elimination solution here. a CIDR value is the number of bits that are lockeed so 10.0.0.0/32 means no range.

Answer is D, 10.0.1.0/24.

Yes D is the answer

Definitely D. It is the only valid VPC CIDR block that does not overlap with the development VPC CIDR block among the options.

The allowed block size is between a /28 netmask and /16 netmask. The CIDR block must not overlap with any existing CIDR block that's associated with the VPC. https://docs.aws.amazon.com/vpc/latest/userguide/configure-your-vpc.html