An administrator is planning a new virtual network named `VNet-Prod` with an address space… — Microsoft Azure Administrator (AZ-104)

An administrator is planning a new virtual network named `VNet-Prod` with an address space of $10.10.0.0/16$ . The virtual network must support the following requirements:
- A subnet for Azure Bastion named `AzureBastionSubnet`.
- A subnet for a VPN Gateway named `GatewaySubnet`.
- An application subnet named `Subnet-App` that will host 60 virtual machines.

Which of the following subnet allocations satisfies these requirements while minimizing IP address waste?

A
AzureBastionSubnet: $10.10.1.0/27$ ; GatewaySubnet: $10.10.2.0/27$ ; Subnet-App: $10.10.3.0/25$
B
AzureBastionSubnet: $10.10.1.0/26$ ; GatewaySubnet: $10.10.2.0/27$ ; Subnet-App: $10.10.3.0/26$ , and route traffic to a firewall virtual appliance using a next hop type of Virtual Network Gateway
AzureBastionSubnet: $10.10.1.0/26$ ; GatewaySubnet: $10.10.2.0/27$ ; Subnet-App: $10.10.3.0/25$ Answer
D
AzureBastionSubnet: $10.10.1.0/26$ ; GatewaySubnet: $10.10.2.0/27$ ; Subnet-App: $10.10.3.0/25$ , and a Private DNS Zone linked directly to Subnet-App

Answer

AzureBastionSubnet:

10.10.1.0/26

; GatewaySubnet:

10.10.2.0/27

; Subnet-App:

10.10.3.0/25

The correct configuration allocates a /26 subnet for Azure Bastion, a /27 subnet for the VPN Gateway, and a /25 subnet for Subnet-App. A /26 prefix is the minimum required size for Azure Bastion. For Subnet-App, hosting 60 virtual machines requires at least 65 IP addresses because Azure reserves 5 IP addresses per subnet (the first four and the last one). A /26 subnet provides 64 total addresses, leaving only 59 usable, which is insufficient. A /25 subnet provides 128 total addresses (123 usable), which meets the requirement of 60 VMs while minimizing waste.

Step-by-Step Solution

Determine the minimum prefix size for Azure Bastion.

Azure Bastion requires a subnet named AzureBastionSubnet with a prefix of at least /26.

To ensure successful deployment and scaling of Azure Bastion host resources.

Calculate the required subnet size for Subnet-App.

Subnet-App needs to support 60 VMs. Since Azure reserves 5 IP addresses in each subnet, the subnet needs a capacity of at least 65 IP addresses. A /26 subnet provides 64 addresses (59 usable), which is too small. A /25 subnet provides 128 addresses (123 usable), which is the smallest standard prefix that satisfies the requirement.

Azure reserves the first four IP addresses and the last IP address in each subnet for its internal services.

Verify correct routing and name resolution configurations.

GatewaySubnet is correctly configured (recommended size is /27 or /28). Route tables for virtual appliances must use Virtual Appliance as the next hop, and Private DNS Zones must be linked at the VNet level rather than the subnet level.

Azure architecture enforces VNet-level scope for private DNS integration and distinct next hop types for virtual appliances vs VPN/ExpressRoute gateways.

Key Concept

Subnet sizing constraints and Azure-specific reserved IP address requirements.

Question

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

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