Which of the following statements about subnet planning is incorrect?

Option B is incorrect . Huawei Cloud explicitly requires subnet CIDR blocks within the same VPC to be unique and not overlap . Allowing overlapping subnets would make local route selection ambiguous and create address conflicts inside the VPC. Huawei's subnet definition therefore states that subnets in a VPC cannot overlap with each other.

Option A is correct for subnet planning: Huawei advises users to plan subnet address ranges carefully because a subnet's CIDR block cannot be changed after creation. This is why future capacity requirements should be considered before allocating subnet prefixes.

Option C is also consistent with Huawei's VPC definition. A subnet represents a unique CIDR block containing an IP address range inside a VPC, and VPC resources requiring private networking are deployed into these subnets. Option D is correct because the subnet CIDR must fall within the VPC's address range. Huawei's network-planning guidance explicitly states that the subnet CIDR block must be within the VPC CIDR block and that subnet CIDR blocks in the VPC must be unique.

Thus, the only incorrect planning statement is B .

Reference topics: VPC and Subnet Planning; CIDR Blocks; Subnet Addressing; VPC Network Design.

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