VNet creation and address space in Azure - Step-by-Step Execution

Process Flow - VNet creation and address space

Start VNet Creation

↓

Define VNet Name

↓

Specify Address Space

↓

Validate Address Space

↓

Create VNet with Address Space

↓

VNet Ready for Use

The flow shows creating a virtual network by naming it, setting its address space, validating it, and then creating it for use.

Execution Sample

Azure

az network vnet create --name MyVNet --resource-group MyResourceGroup --address-prefix 10.0.0.0/16

This command creates a virtual network named MyVNet with the address space 10.0.0.0/16 in the specified resource group.

Process Table

Step	Action	Input	Validation	Result
1	Start VNet creation	N/A	N/A	Ready to define VNet
2	Define VNet name	MyVNet	Name valid	Name accepted
3	Specify address space	10.0.0.0/16	CIDR valid, no overlap	Address space accepted
4	Validate address space	10.0.0.0/16	Valid CIDR block	Validation successful
5	Create VNet	Name: MyVNet, Address: 10.0.0.0/16	N/A	VNet created successfully
6	VNet ready	N/A	N/A	VNet available for resources

💡 VNet creation completes after successful validation and creation steps.

Status Tracker

Variable	Start	After Step 2	After Step 3	After Step 5	Final
VNetName	undefined	MyVNet	MyVNet	MyVNet	MyVNet
AddressSpace	undefined	undefined	10.0.0.0/16	10.0.0.0/16	10.0.0.0/16
VNetStatus	not created	not created	not created	created	available

Key Moments - 3 Insights

Why must the address space be a valid CIDR block?

Because the address space defines the IP range for the VNet, it must be a valid CIDR to ensure proper network routing and avoid conflicts, as shown in step 4 of the execution table.

What happens if the VNet name is invalid?

The creation process stops at step 2 because the name must follow Azure naming rules; invalid names prevent proceeding to address space specification.

Can the address space overlap with existing VNets?

No, overlapping address spaces cause conflicts. Validation in step 3 ensures no overlap before creation.

Visual Quiz - 3 Questions

Look at the execution table, what is the address space after step 3?

A undefined

B 10.0.0.0/16

C 192.168.1.0/24

D N/A

💡 Hint

Check the 'AddressSpace' variable in variable_tracker after step 3.

At which step does the VNet status change to 'created'?

A Step 5

B Step 3

C Step 2

D Step 6

💡 Hint

Look at the 'VNetStatus' variable in variable_tracker and the execution_table result column.

If the address space was invalid, what would happen in the execution flow?

A Name validation fails at step 2

B Creation proceeds normally

C Validation fails at step 4 and stops

D VNet is created with default address space

💡 Hint

Refer to step 4 in the execution_table where address space validation occurs.

Concept Snapshot

VNet creation requires a unique name and a valid address space in CIDR format.
The address space defines the IP range for resources.
Azure validates the address space for correctness and overlap.
After validation, the VNet is created and ready for use.
Use Azure CLI command: az network vnet create --name <name> --resource-group <group> --address-prefix <CIDR>

Full Transcript

Creating a Virtual Network (VNet) in Azure starts by choosing a name and specifying an address space in CIDR format. The address space is the range of IP addresses the VNet will use. Azure checks that the name is valid and that the address space is a proper CIDR block without overlapping existing networks. Once validated, the VNet is created and becomes available for deploying resources. This process ensures network organization and avoids IP conflicts.

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