An administrator is configuring a new virtual network named `vnet-prod` in an Azure subscr… — Microsoft Azure Administrator (AZ-104)

An administrator is configuring a new virtual network named `vnet-prod` in an Azure subscription. The virtual network is assigned the address space $10.15.4.0/22$ . The administrator must create the following subnets:

* A subnet named `Subnet-App` to host up to $125$ virtual machines.
* A subnet to support an Azure Bastion host.
* A subnet named `GatewaySubnet` to support a VPN Gateway.

To conserve IP addresses for future expansion, the administrator wants to allocate the minimum required address space to each subnet. Which configuration of subnet prefix lengths should the administrator use?

A
$/25$ for `Subnet-App`, $/26$ for `AzureBastionSubnet`, and $/29$ for `GatewaySubnet`
$/24$ for `Subnet-App`, $/26$ for `AzureBastionSubnet`, and $/29$ for `GatewaySubnet`Answer
C
$/24$ for `Subnet-App`, $/27$ for `AzureBastionSubnet`, and $/29$ for `GatewaySubnet`
D
$/24$ for `Subnet-App`, $/26$ for `AzureBastionSubnet`, and $/30$ for `GatewaySubnet`

Answer

The configuration using

/24

for `Subnet-App`,

/26

for `AzureBastionSubnet`, and

/29

for `GatewaySubnet`.

The correct configuration uses

/24

for `Subnet-App` (providing

251

usable addresses, which accommodates the required

125

hosts after subtracting the

5

Azure reserved IP addresses),

/26

for `AzureBastionSubnet` (meeting the minimum prefix requirement of

/26

for Azure Bastion hosts), and

/29

for `GatewaySubnet` (meeting the minimum prefix requirement of

/29

for Azure VPN Gateways).

Step-by-Step Solution

Calculate the size required for `Subnet-App`.

/24

subnet prefix.

To host

125

virtual machines, the subnet must also accommodate the

5

IP addresses reserved by Azure (the first

4

and the last

1

address of the subnet). This requires a total of

125 + 5 = 130

IP addresses. A

/25

subnet provides

128

IP addresses (

123

usable), which is insufficient. A

/24

subnet provides

256

IP addresses (

251

usable), which is the minimum sufficient size.

Determine the size requirement for the Azure Bastion subnet.

/26

subnet prefix.

Azure Bastion must be deployed in a subnet named exactly `AzureBastionSubnet` and configured with a prefix length of

/26

or larger (e.g.,

/26

/25

/24

). A

/27

subnet is too small and is not supported.

Determine the size requirement for `GatewaySubnet`.

/29

subnet prefix.

The subnet used for an Azure Virtual Network Gateway must be named `GatewaySubnet`. It must have a minimum prefix length of

/29

to accommodate the gateway instances and Azure's

5

reserved IPs. A

/30

subnet is invalid as it only contains

4

total IP addresses.

Key Concept

Azure Virtual Network subnet sizing constraints, Azure reserved IP addresses, and specific subnet size requirements for Azure Bastion and VPN Gateways.

Question

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

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