VNet creation and address space in Azure - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding VNet Address Space Overlaps

You have two Azure Virtual Networks (VNets). VNet A has the address space 10.0.0.0/16. VNet B has the address space 10.0.1.0/24. What will happen if you try to peer these two VNets?

A The peering will succeed because 10.0.1.0/24 is a subset of 10.0.0.0/16, so they are compatible.

B The peering will fail because the address spaces overlap, which is not allowed in VNet peering.

C The peering will succeed but traffic between VNets will be blocked due to overlapping address spaces.

D The peering will succeed only if you enable gateway transit on both VNets.

💡 Hint

Think about whether overlapping IP ranges are allowed in VNet peering.

Azure does not allow peering between VNets that have overlapping IP address spaces. Since 10.0.1.0/24 is within 10.0.0.0/16, the address spaces overlap, so peering will fail.

❓ Configuration

intermediate

Choosing a Valid Address Space for a New VNet

You want to create a new Azure VNet in a subscription that already has a VNet with address space 192.168.0.0/24. Which of the following address spaces can you assign to the new VNet without causing conflicts?

A 192.168.1.0/24

B 192.168.0.128/25

C 192.168.0.0/23

D 192.168.0.64/26

💡 Hint

Check if the new address space overlaps with the existing 192.168.0.0/24 range.

192.168.1.0/24 does not overlap with 192.168.0.0/24, so it is a valid choice. The other options overlap with the existing VNet's address space.

❓ Architecture

advanced

Designing VNet Address Spaces for Multi-Region Deployment

You are designing VNets for a multi-region Azure deployment. You want to avoid address space conflicts and allow future peering between VNets. Which approach is best for assigning address spaces?

A Use overlapping address spaces but rely on network security groups to isolate traffic.

B Assign the same address space to all VNets in different regions to simplify routing.

C Assign non-overlapping, contiguous CIDR blocks to each VNet, for example, 10.0.0.0/16 for region 1 and 10.1.0.0/16 for region 2.

D Assign random address spaces without coordination and fix conflicts when they arise.

💡 Hint

Think about how to avoid conflicts and enable peering in the future.

Assigning non-overlapping, contiguous CIDR blocks per region avoids conflicts and allows easy peering and routing between VNets.

❓ security

advanced

Impact of Overlapping Address Spaces on Network Security

You have two VNets with overlapping address spaces that are connected via VPN Gateway. What is a likely security risk in this scenario?

A Traffic between VNets will be encrypted, so there is no security risk.

B VPN Gateway will prevent any communication between VNets with overlapping address spaces.

C Network security groups will automatically block all traffic between overlapping VNets.

D Overlapping address spaces can cause traffic to be misrouted, potentially exposing sensitive data to the wrong VNet.

💡 Hint

Consider what happens when IP addresses overlap in different networks.

Overlapping address spaces can cause routing confusion, leading to traffic being sent to unintended destinations, which is a security risk.

❓ service_behavior

expert

Behavior of Azure VNet with Multiple Address Spaces

You create an Azure VNet and assign two address spaces: 10.0.0.0/16 and 10.1.0.0/24. You then create a subnet with address range 10.1.0.0/25. What is the behavior of this subnet within the VNet?

A The subnet is valid and usable because its address range is within one of the VNet's address spaces.

B The subnet is invalid because subnets cannot be created from the second address space of a VNet.

C The subnet overlaps with the VNet's primary address space and will cause deployment failure.

D The subnet must be larger than /24 to be valid within the VNet.

💡 Hint

Think about how VNets support multiple address spaces and subnet creation.

Azure VNets can have multiple address spaces. Subnets can be created from any of these address spaces as long as they do not overlap with other subnets.

Practice

1. What does the address space in an Azure Virtual Network (VNet) define?

easy

A. The physical location of the VNet data center

B. The number of virtual machines allowed in the VNet

C. The range of IP addresses available for resources inside the VNet

D. The security rules applied to the VNet

Solution

1. Step 1: Understand the purpose of address space in VNet

   The address space specifies the IP address range that the VNet can use for its resources.

2. Step 2: Differentiate from other VNet properties

   Physical location, VM count, and security rules are separate configurations unrelated to address space.

3. Final Answer:

   The range of IP addresses available for resources inside the VNet -> Option C

4. Quick Check:

   Address space = IP range [OK]

Hint: Address space means IP range inside the VNet [OK]

Common Mistakes:

• Confusing address space with location
• Thinking address space limits VM count
• Mixing address space with security settings

2. Which Azure CLI command correctly creates a VNet named MyVNet with address space 10.0.0.0/16 in resource group MyGroup?

easy

A. az network vnet create --name MyVNet --resource-group MyGroup --address-prefixes 10.0.0.0/16

B. az network vnet create --vnet-name MyVNet --group MyGroup --address-space 10.0.0.0/16

C. az vnet create --name MyVNet --resource-group MyGroup --address 10.0.0.0/16

D. az network vnet new --name MyVNet --resource-group MyGroup --address-prefix 10.0.0.0/16

Solution

1. Step 1: Identify correct Azure CLI syntax for VNet creation

   The correct command uses az network vnet create with parameters --name, --resource-group, and --address-prefixes.

2. Step 2: Check each option for syntax correctness

   az network vnet create --name MyVNet --resource-group MyGroup --address-prefixes 10.0.0.0/16 matches the correct syntax. Other options use incorrect commands (like az vnet create or az network vnet new) or parameter names (like --vnet-name, --group, --address-space, --address, --address-prefix).

3. Final Answer:

   az network vnet create --name MyVNet --resource-group MyGroup --address-prefixes 10.0.0.0/16 -> Option A

4. Quick Check:

   Correct CLI syntax = az network vnet create --name MyVNet --resource-group MyGroup --address-prefixes 10.0.0.0/16 [OK]

Hint: Use --address-prefixes for IP range in az network vnet create [OK]

Common Mistakes:

• Using wrong parameter names like --address-space
• Using incorrect commands like az vnet create
• Mixing resource group parameter names

3. Given the Azure CLI command:

az network vnet create --name TestVNet --resource-group TestGroup --address-prefixes 192.168.0.0/24

What is the size of the IP address range allocated to TestVNet?

medium

A. 1024 IP addresses

B. 65,536 IP addresses

C. 16 IP addresses

D. 256 IP addresses

Solution

1. Step 1: Understand CIDR notation /24

   The /24 means the first 24 bits are fixed, leaving 8 bits for host addresses.

2. Step 2: Calculate number of IP addresses

   2^8 = 256 IP addresses are available in the 192.168.0.0/24 range.

3. Final Answer:

   256 IP addresses -> Option D

4. Quick Check:

   /24 = 256 IPs [OK]

Hint: /24 means 256 IP addresses in the range [OK]

Common Mistakes:

• Confusing /24 with /16 or /28
• Miscounting IP addresses as 1024 or 65,536
• Ignoring subnet mask meaning

4. You try to create a VNet with the command:

az network vnet create --name MyVNet --resource-group MyGroup --address-prefixes 10.0.0.0/16 10.0.0.0/24

But it fails. What is the most likely reason?

medium

A. The VNet name is already in use

B. You cannot specify overlapping address spaces in one VNet

C. The resource group name is invalid

D. The command requires a location parameter

Solution

1. Step 1: Analyze the address prefixes given

   The prefixes 10.0.0.0/16 and 10.0.0.0/24 overlap because /24 is a subset of /16.

2. Step 2: Understand Azure VNet address space rules

   Azure does not allow overlapping address spaces within the same VNet.

3. Final Answer:

   You cannot specify overlapping address spaces in one VNet -> Option B

4. Quick Check:

   Overlapping address spaces cause failure [OK]

Hint: Avoid overlapping IP ranges in one VNet [OK]

Common Mistakes:

• Assuming location is mandatory for this error
• Thinking resource group name causes this error
• Believing VNet name conflict causes this error

5. You want to create a VNet with two non-overlapping address spaces: 10.1.0.0/16 and 10.2.0.0/16. Which command correctly creates this VNet named MultiVNet in resource group RG1?

hard

A. az network vnet create --name MultiVNet --resource-group RG1 --address-prefixes 10.1.0.0/16 10.2.0.0/16

B. az network vnet create --name MultiVNet --resource-group RG1 --address-prefix 10.1.0.0/16,10.2.0.0/16

C. az network vnet create --name MultiVNet --resource-group RG1 --address-prefixes 10.1.0.0/16,10.2.0.0/16

D. az network vnet create --name MultiVNet --resource-group RG1 --address-space 10.1.0.0/16 10.2.0.0/16

Solution

1. Step 1: Check correct parameter for multiple address spaces

   The parameter --address-prefixes accepts multiple space-separated CIDR blocks.

2. Step 2: Validate syntax for multiple prefixes

   az network vnet create --name MultiVNet --resource-group RG1 --address-prefixes 10.1.0.0/16 10.2.0.0/16 uses space-separated prefixes correctly. Using commas to separate prefixes, singular --address-prefix, or --address-space instead of --address-prefixes is invalid.

3. Final Answer:

   az network vnet create --name MultiVNet --resource-group RG1 --address-prefixes 10.1.0.0/16 10.2.0.0/16 -> Option A

4. Quick Check:

   Multiple prefixes = space-separated with --address-prefixes [OK]

Hint: Use --address-prefixes with spaces for multiple CIDRs [OK]

Common Mistakes:

• Using commas instead of spaces between prefixes
• Using --address-prefix instead of --address-prefixes
• Using --address-space which is invalid