Subnets within a VNet in Azure - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a virtual network with an address space.

Azure

resource "azurerm_virtual_network" "example" {
  name                = "example-vnet"
  location            = "eastus"
  resource_group_name = "example-resources"
  address_space       = ["[1]"]
}

Drag options to blanks, or click blank then click option'

A172.16.0.0/12

B192.168.1.0/24

C10.0.0.0/16

D255.255.255.0

Attempts:

3 left

💡 Hint

Common Mistakes

Using a subnet mask like '255.255.255.0' instead of CIDR notation.

Using a public IP range instead of a private IP range.

The address space defines the IP range for the virtual network. "10.0.0.0/16" is a common private IP range used for VNets.

2fill in blank

medium

Complete the code to define a subnet within the virtual network.

Azure

resource "azurerm_subnet" "example_subnet" {
  name                 = "example-subnet"
  resource_group_name  = "example-resources"
  virtual_network_name = azurerm_virtual_network.example.name
  address_prefixes     = ["[1]"]
}

Drag options to blanks, or click blank then click option'

A10.0.0.0/16

B10.0.1.0/24

C192.168.1.0/24

D172.16.0.0/12

Attempts:

3 left

💡 Hint

Common Mistakes

Using an address prefix outside the VNet's address space.

Using the same prefix as the VNet address space.

The subnet address prefix must be a subset of the virtual network's address space. "10.0.1.0/24" fits inside "10.0.0.0/16".

3fill in blank

hard

Fix the error in the subnet address prefix to be valid within the VNet.

Azure

resource "azurerm_subnet" "wrong_subnet" {
  name                 = "wrong-subnet"
  resource_group_name  = "example-resources"
  virtual_network_name = azurerm_virtual_network.example.name
  address_prefixes     = ["[1]"]
}

Drag options to blanks, or click blank then click option'

A10.0.2.0/24

B10.0.0.0/16

C10.1.0.0/24

D192.168.1.0/24

Attempts:

3 left

💡 Hint

Common Mistakes

Using a subnet prefix that overlaps the entire VNet.

Using an address prefix outside the VNet range.

The subnet prefix must be within the VNet's address space (10.0.0.0/16). "10.0.2.0/24" is valid, while others are either too large or outside the range.

4fill in blank

hard

Fill both blanks to define a subnet with network security group association.

Azure

resource "azurerm_subnet" "secure_subnet" {
  name                 = "secure-subnet"
  resource_group_name  = "example-resources"
  virtual_network_name = azurerm_virtual_network.example.name
  address_prefixes     = ["[1]"]
  network_security_group_id = azurerm_network_security_group.example.[2]
}

Drag options to blanks, or click blank then click option'

A10.0.3.0/24

Bid

Cname

Dlocation

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'name' or 'location' instead of 'id' for NSG association.

Using an invalid subnet prefix outside the VNet.

The subnet address prefix must be within the VNet range, here "10.0.3.0/24". The network security group ID property is "id" to link the NSG resource.

5fill in blank

hard

Fill all three blanks to define a virtual network with two subnets.

Azure

resource "azurerm_virtual_network" "multi_subnet_vnet" {
  name                = "multi-subnet-vnet"
  location            = "eastus"
  resource_group_name = "example-resources"
  address_space       = ["[1]"]
}

resource "azurerm_subnet" "subnet1" {
  name                 = "subnet1"
  resource_group_name  = "example-resources"
  virtual_network_name = azurerm_virtual_network.multi_subnet_vnet.name
  address_prefixes     = ["[2]"]
}

resource "azurerm_subnet" "subnet2" {
  name                 = "subnet2"
  resource_group_name  = "example-resources"
  virtual_network_name = azurerm_virtual_network.multi_subnet_vnet.name
  address_prefixes     = ["[3]"]
}

Drag options to blanks, or click blank then click option'

A10.1.0.0/16

B10.1.1.0/24

C10.1.2.0/24

D10.2.0.0/24

Attempts:

3 left

💡 Hint

Common Mistakes

Using subnet prefixes outside the VNet address space.

Using overlapping subnet prefixes.

The VNet address space is "10.1.0.0/16". The two subnets must have prefixes inside this range, such as "10.1.1.0/24" and "10.1.2.0/24".

Practice

1. What is the main purpose of creating subnets within a Virtual Network (VNet) in Azure?

easy

A. To create virtual machines directly inside the VNet

B. To divide the VNet into smaller IP address ranges for better organization and security

C. To connect different VNets together automatically

D. To increase the total IP address space of the VNet

Solution

1. Step 1: Understand the role of subnets in a VNet

   Subnets split a VNet into smaller parts, each with its own IP range.

2. Step 2: Identify the purpose of subnetting

   Subnetting helps organize resources and apply security rules within the VNet.

3. Final Answer:

   To divide the VNet into smaller IP address ranges for better organization and security -> Option B

4. Quick Check:

   Subnet purpose = divide and organize IP ranges [OK]

Hint: Subnets split IP space inside a VNet for organization [OK]

Common Mistakes:

• Thinking subnets increase total IP space
• Confusing subnets with VNet peering
• Believing subnets create VMs automatically

2. Which of the following is the correct way to define a subnet within an Azure VNet using CIDR notation?

easy

A. 10.0.1.0/24

B. 10.0.0.256/24

C. 10.0.0.0/16

D. 10.0.0.0/33

Solution

1. Step 1: Review valid CIDR notation for subnets

   CIDR notation uses an IP address and a prefix length between 0 and 32 for IPv4.

2. Step 2: Check each option for validity

   10.0.0.0/16 is a VNet range, not a subnet. 10.0.1.0/24 is a valid subnet inside 10.0.0.0/16. 10.0.0.256/24 has an invalid IP (256 is out of range). 10.0.0.0/33 has an invalid prefix length (33 is too large).

3. Final Answer:

   10.0.1.0/24 -> Option A

4. Quick Check:

   Valid subnet CIDR = 10.0.1.0/24 [OK]

Hint: Subnet CIDR must have valid IP and prefix ≤ 32 [OK]

Common Mistakes:

• Using IP octets above 255
• Using prefix length greater than 32
• Confusing VNet and subnet CIDR sizes

3. Given a VNet with address space 192.168.0.0/16, which subnet CIDR block is valid and fits inside this VNet?

medium

A. 192.168.1.0/24

B. 192.169.0.0/24

C. 192.168.0.0/15

D. 10.0.0.0/24

Solution

1. Step 1: Understand the VNet address space

   The VNet covers IPs from 192.168.0.0 to 192.168.255.255 (a /16 block).

2. Step 2: Check which subnet fits inside the VNet

   192.168.1.0/24 (192.168.1.0/24) fits inside the VNet range. 192.169.0.0/24 is outside the 192.168.x.x range. 192.168.0.0/15 has a /15 prefix which is larger than the VNet's /16, so it extends outside. 10.0.0.0/24 is a different private IP range.

3. Final Answer:

   192.168.1.0/24 -> Option A

4. Quick Check:

   Subnet inside VNet range = 192.168.1.0/24 [OK]

Hint: Subnet must be fully inside VNet IP range [OK]

Common Mistakes:

• Choosing subnet outside VNet range
• Using larger prefix than VNet
• Confusing private IP ranges

4. You tried to create a subnet with CIDR 10.1.0.0/16 inside a VNet with address space 10.0.0.0/24. What is the problem?

medium

A. The subnet CIDR is invalid because it uses a private IP range

B. The subnet CIDR is too small for a subnet

C. The subnet CIDR overlaps with another subnet

D. The subnet CIDR is larger than the VNet address space and does not fit inside

Solution

1. Step 1: Compare subnet and VNet address spaces

   The VNet covers 10.0.0.0 to 10.0.0.255 (/24). The subnet 10.1.0.0/16 covers 10.1.0.0 to 10.1.255.255, which is outside the VNet range.

2. Step 2: Identify the error

   The subnet CIDR must be fully inside the VNet's address space. Here, it is larger and outside the VNet.

3. Final Answer:

   The subnet CIDR is larger than the VNet address space and does not fit inside -> Option D

4. Quick Check:

   Subnet must fit inside VNet range [OK]

Hint: Subnet CIDR must be inside VNet CIDR, not bigger [OK]

Common Mistakes:

• Ignoring subnet size vs VNet size
• Thinking private IP ranges are invalid
• Assuming overlap without checking

5. You have a VNet with address space 172.16.0.0/16. You want to create three subnets: 172.16.0.0/18, 172.16.64.0/18, and 172.16.128.0/17. Which statement is true about these subnets?

hard

A. The second subnet is outside the VNet address space

B. The third subnet overlaps with the first two subnets

C. All three subnets fit inside the VNet without overlapping

D. The subnet sizes are invalid for this VNet

Solution

1. Step 1: Analyze the VNet and subnet ranges

   The VNet covers 172.16.0.0 to 172.16.255.255 (/16). The first subnet covers 172.16.0.0 to 172.16.63.255 (/18). The second covers 172.16.64.0 to 172.16.127.255 (/18). The third covers 172.16.128.0 to 172.16.255.255 (/17).

2. Step 2: Check for overlaps

   The subnets cover distinct ranges: first 172.16.0.0-172.16.63.255, second 172.16.64.0-172.16.127.255, third 172.16.128.0-172.16.255.255. No overlaps, all fit within the VNet.

3. Final Answer:

   All three subnets fit inside the VNet without overlapping -> Option C

4. Quick Check:

   All three subnets fit without overlapping [OK]

Hint: Check subnet ranges carefully for overlaps [OK]

Common Mistakes:

• Miscalculating subnet ranges and thinking they overlap
• Confusing prefix lengths and their sizes
• Ignoring subnet boundaries