Configure private and public IP addresses

Private IP addresses are used within a virtual network and are not reachable from the internet. These addresses allow Azure resources to communicate with each other in a secure environment. Azure automatically assigns a private IP address from the address range that you specify when creating a VNet.

When setting up a private IP for an Azure Virtual Machine (VM) or any other resource, you have two options:

• Dynamic Allocation: Azure DHCP assigns the private IP address. The address is released if the resource is deleted or the network interface (NIC) is disassociated.
• Static Allocation: You manually assign a static private IP address. This address remains with the resource until you change or remove it.

To configure a private IP address for an Azure VM, you can follow these steps:

1. Navigate to the Azure portal.
2. Go to the Virtual Machine’s settings, and select Networking.
3. Click on the Network Interface associated with your VM.
4. Under IP configurations, select the IP configuration you want to modify.
5. Choose either dynamic or static assignment and, if applicable, specify the static IP address you want to use.

Azure reserves the first four addresses in each subnet for its use; therefore, they cannot be assigned to resources.

Public IP Addresses

Public IP addresses allow Azure resources to communicate with external networks, including the internet. You can assign these IP addresses to resources such as VMs, internet-facing load balancers, or VPN gateways.

Azure offers two types of public IP addresses:

• Dynamic: The public IP address can change if the resource it’s associated with is stopped (deallocated) and then started again.
• Static (reserved): The public IP address is fixed and does not change. It’s reserved for your subscription until you delete it.

Configuring a public IP address involves creating a public IP resource and associating it with a VM or service:

1. Navigate to the Azure portal.
2. Click on “Create a resource” and search for “Public IP address”.
3. Fill in the details such as Name, Subscription, Resource group.
4. Choose whether you want a static or dynamic IP.
5. Select the appropriate SKU (Basic or Standard).
6. Click “Create” to provision the public IP address.
7. Once created, associate the public IP address with the intended Azure resource.

You may assign public IP addresses to resources either directly or through a load balancer. Using Azure Load Balancer helps distribute traffic to multiple VMs and ensures high availability and reliability.

Considerations for IP Address Management

Understanding Azure’s IP address capabilities is essential for network planning and design:

• IP Address Availability: Check the availability of IP addresses within the desired Azure region and subscription limits.
• Network Security Groups (NSGs): While configuring IP addresses, remember to update NSGs to allow or deny traffic to your VMs.
• Cost: Static public IP addresses incur cost as long as they are provisioned, even if not associated with an active resource.
• DNS: Consider integrating your IP address configuration with Azure DNS services for name resolution.
• SKU: Public IP addresses come in two SKUs: Basic and Standard, which differ in features such as availability, and support for availability zones.

In summary, configuring private and public IP addresses in Azure is a critical skill for an Azure Administrator, which involves understanding the differences between address types, their use cases, and implications for network security and reliability. It is a balancing act between ensuring seamless connectivity and maintaining best practices for security and cost management.