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Question

Difficulty: MediumCreate and Configure Virtual Networks and Subnets

An administrator is configuring a virtual network named `vnet-office` with an address space of 192.168.0.0/22192.168.0.0/22. The virtual network currently contains two subnets:
- `Subnet-A` with an address prefix of 192.168.0.0/24192.168.0.0/24
- `Subnet-B` with an address prefix of 192.168.1.0/24192.168.1.0/24

The administrator wants to create a third subnet named `Subnet-C` that provides the maximum number of usable IP addresses from the remaining address space.

Statement: The administrator can configure `Subnet-C` with the address prefix 192.168.2.0/23192.168.2.0/23 without causing any address space overlap.

Is this statement true or false?

Answer: Answer

Answer

True
The proposed subnet prefix 192.168.2.0/23192.168.2.0/23 represents the exact remaining IP address space in the virtual network (192.168.2.0192.168.2.0 through 192.168.3.255192.168.3.255), resulting in no overlaps and maximizing the subnet size.

Step-by-Step Solution

1
Identify the total IP range allocated to the virtual network.
The prefix 192.168.0.0/22192.168.0.0/22 covers the range from 192.168.0.0192.168.0.0 to 192.168.3.255192.168.3.255 (total of 10241024 addresses).
Determining the outer boundary of the network is necessary to find the remaining unassigned blocks.
2
Calculate the range of addresses occupied by the existing subnets.
`Subnet-A` (192.168.0.0/24192.168.0.0/24) occupies 192.168.0.0192.168.0.0 to 192.168.0.255192.168.0.255. `Subnet-B` (192.168.1.0/24192.168.1.0/24) occupies 192.168.1.0192.168.1.0 to 192.168.1.255192.168.1.255. The occupied range is 192.168.0.0192.168.0.0 to 192.168.1.255192.168.1.255.
This identifies which IPs are already allocated to prevent overlapping subnets.
3
Define the remaining free address space and find the largest single CIDR block that fits it.
The free space is 192.168.2.0192.168.2.0 to 192.168.3.255192.168.3.255. This block size is 512512 addresses, which corresponds to a /23/23 subnet mask. The block is aligned on a /23/23 boundary, meaning 192.168.2.0/23192.168.2.0/23 perfectly matches this range.
This confirms that the proposed prefix is mathematically valid and fully utilizes the remaining space without overlap.

Key Concept

Determining maximum non-overlapping subnet size in an Azure Virtual Network.
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Topics

Create and Configure Virtual Networks and Subnets