ANS-C01 Network Implementation Practice Question

A company has a VPC with an IPv4 CIDR of 10.0.0.0/16. They need to add an additional non-overlapping CIDR to the VPC. What is a valid CIDR block they can add?

⚠ Common exam trap

It's easy for candidates to assume any non-overlapping RFC 1918 block is valid, but they overlook that the new CIDR must not be a subset or superset of the existing CIDR, and AWS specifically requires the new block to be non-overlapping at the VPC level, not just at the subnet level.

Answer choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

✓

10.1.0.0/16

(10.1.0.0/16) is correct because it is a non-overlapping IPv4 CIDR block that does not conflict with the existing VPC CIDR of 10.0.0.0/16. In AWS, when adding a secondary CIDR to a VPC, the new block must be from the private IP address ranges (RFC 1918) and must not overlap with any existing CIDR blocks in the VPC. The 10.1.0.0/16 range is entirely separate from 10.0.0.0/16, as they are different /16 subnets within the 10.0.0.0/8 space.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

✗
10.0.1.0/24
Why it's wrong here
Subset of existing CIDR, overlaps.
✓
10.1.0.0/16
Why this is correct
Non-overlapping, valid addition.
✗
10.0.0.0/8
Why it's wrong here
Overlaps with existing CIDR.
✗
10.0.0.0/16
Why it's wrong here
Same CIDR, not additional.

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ANS-C01 Network Implementation Practice Question

Why each option matters

Option-by-option breakdown

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