Public IP addresses enable Azure VMs and resources to communicate directly with the Internet. These addresses are routable and reachable across the internet. On the other hand, Internal IP addresses are also known as Private IP addresses, used for communication within an Azure Virtual Network (VNet) and your on-premises location in a hybrid scenario via VPN or ExpressRoute. These Internal IPs are not accessible directly from the internet.
Public IP Addresses
Azure provides two types of Public IP addresses: Static and Dynamic.
- Static Public IPs: In Azure, when you assign a static public IP address to a VM, that address remains the same throughout the VM’s lifecycle. Even if you stop/deallocate the VM, the address remains the same.
- Dynamic Public IPs: Conversely, when you allocate a dynamic public IP address to a VM, Azure assigns it from a pool of available IPs each time you stop and deallocate the VM.
Choosing between these two depends on your specific needs. If your resources require a constant public IP address (e.g., that is whitelisted), you should choose a static public IP address. However, if a VM or service only needs brief or intermittent internet access, a dynamic public IP address would make more sense.
Internal IP Addresses
Internal IP addresses are private to the user and its Azure AD Tenancy. Internal IP addresses are crucial for communication within an Azure virtual network (VNet) and your local network via VPN or Azure ExpressRoute, and between Azure resources.
Azure offers two types of Internal IP addresses: Static and Dynamic. The dynamic allocation method is default, but a static IP can be crucial when you host a server or DNS server, or for certain database services that need a fixed IP address.
- Static Internal IPs: When you assign a static internal IP address, it remains with the resource until you explicitly remove it.
- Dynamic Internal IPs: When you allocate a dynamic internal IP address, Azure assigns it from a pool of available IPs in the VNet. Every time the VM is restarted, it will be assigned a new internal IP if the VM was shocked down (deallocated).
A Recommended Strategy
The Azure Stack Hub IP strategy should be flexible enough to meet your business, operational, and compliance requirements. Here’s a suggested blueprint:
- For Public IP address usage, the recommended strategy is to consider the static allocation method for services that require a consistent IP address. Utilize dynamic allocation for temporary usage or where IP consistency isn’t paramount.
- For Internal IP addresses, default dynamic allocation yields higher flexibility, but for sustenance of network configurations, it’s advisable to deploy a static internal IP address strategy wherever a fixed IP address is a pre-requisite.
Remember to plan both the public and internal IP strategies in line with your future growth and scalability needs. While determining an IP strategy, also consider high availability, load balancing, and other such factors that could affect the availability and performance of applications hosted on Azure Stack Hub.
In conclusion, it is essential to develop a robust internal and public IP strategy that aligns with your organization’s goals, functionalities, and growth projections, while also accommodating an effective hybrid cloud with Azure Stack Hub.
Practice Test
True or False: Public IP addresses are globally unique, and Internal IP addresses are unique within an organization or a location.
- True
- False
Answer: True
Explanation: Public IP addresses are globally unique and are used over the internet, whereas internal IP addresses are unique within an organization or a specific location only.
Which of the following is a common strategy for assigning public IP addresses in Azure?
- A. Assigning a single static IP address to each VM
- B. Using DHCP to dynamically assign IP addresses
- C. Using an Azure Load Balancer
- D. Assigning each VM a unique IP address from a range of private IP addresses
Answer: C. Using an Azure Load Balancer
Explanation: Azure Load Balancer distributes incoming traffic among healthy service instances in cloud services or virtual machines in a load balancer set.
True or False: An end-user’s device will typically have an internal IP address that’s on the same network as the server it’s communicating with.
- True
- False
Answer: False
Explanation: An end-user’s device will typically have an internal IP address that is on a different network, separated by routers and firewalls.
Which of the following can an Azure Stack Hub operator do to manage public IP addresses?
- A. Add or remove public IP addresses
- B. Configure DNS settings
- C. Both A and B
- D. None of the above
Answer: C. Both A and B
Explanation: The Azure Stack Hub operator has the ability to add or remove public IP addresses, besides configuring DNS settings.
True or False: It is recommended to use Static IP addresses for servers that host websites.
- True
- False
Answer: True
Explanation: It is recommended to have a static IP for servers that host websites, because if the IP changes, the DNS records will need to be updated which might cause the website to be unreachable.
Multiple public IP addresses cannot be associated with a single virtual machine in Azure.
- A. True
- B. False
Answer: B. False
Explanation: It is possible to associate multiple public IP addresses with a single virtual machine through the use of network interfaces.
Which of the following is not a type of IP address in Azure?
- A. Dynamic public IP address
- B. Static public IP address
- C. Secondary private IP address
- D. Primary public IP address
Answer: D. Primary public IP address
Explanation: In Azure, there is a primary private IP address but there’s no such concept as a primary public IP address.
True or False: In Azure Stack Hub, it is recommended to allocate Internal IP addresses dynamically.
- True
- False
Answer: True
Explanation:Dynamic allocation of internal IP addresses in Azure Stack Hub allows for efficient use of addresses and ease of management.
Having private IP address range overlap in Azure Stack Hub is a good practice.
- A. True
- B. False
Answer: B. False
Explanation: Having overlapping IP address spaces can lead to routing issues and is generally not a good practice.
In Azure, the use of public IP addresses is recommended:
- A. To provide internet-facing services
- B. For communication between resources in the same virtual network
- C. For all communication between Azure resources
- D. For communication inside a subnet
Answer: A. To provide internet-facing services
Explanation: Public IP addresses in Azure are mainly used for providing Internet-facing services and allowing secure access to VMs. For internal communication, private IP addresses are more ideal.
Interview Questions
What is the fundamental difference between a public IP address and an internal IP address in Azure Stack Hub?
A public IP address in Azure Stack Hub is designed to provide Azure resources with an outward-facing, internet-routable identity. On the other hand, an internal IP address is used for communication within the Azure Stack Hub network.
How many users can be depended on a public IP address strategy in Azure Stack Hub?
The number of users that can be supported by a public IP address strategy can be quite high, with the exact number depending largely on the scalability and elasticity of the Azure Stack Hub environment and its resources.
What are the benefits of using an internal IP address strategy in the Azure Stack Hub environment?
The benefits include enhanced security since the internal IPs are not accessible from the public internet. Furthermore, it simplifies the network management and allows for effective communication within the Azure Stack Hub environment.
Can a Virtual Machine in Azure Stack Hub have both a public and private IP address?
Yes, a virtual machine in Azure Stack Hub can have both a public and private IP address, enabling it to communicate both within the network (using the private address) and with the Internet (via the public IP).
What is the role of Azure Stack Hub firewall in public and internal IP strategy?
The Azure Stack Hub firewall inspects incoming and outgoing traffic from both public and internal IP addresses, to enforce security rules and filter traffic.
How can a user or a system administrator obtain a public IP address in Azure Stack Hub?
A user or system administrator can obtain a public IP address by requesting one from Azure portal, Azure PowerShell, or Azure CLI.
If a Public IP address is attached to a virtual machine, does it stay with the virtual machine when it is stopped or deallocated in Azure Stack Hub?
Yes, in general, the assigned public IP address remains associated with the virtual machine, even when it is stopped or deallocated.
What type of deployment is recommended for using a public IP strategy in the Azure Stack Hub environment?
Public IP strategy is commonly used in Enterprise-grade, production environments, to provide services to customers over the internet.
In Azure Stack Hub, can you switch from an internal IP address strategy to a public IP address strategy?
Yes, with appropriate permissions, it’s possible to switch from an internal IP address strategy to a public IP address in Azure Stack Hub.
What is the primary reason to recommend an internal IP strategy over a public IP strategy in Azure Stack Hub?
The primary reason would be to enhance security and prevent unauthorized access from the internet, as internal IP addresses are not routable from the public internet.
Why is a subnet part of an effective internal IP strategy in Azure Stack Hub?
Subnets help to segment and organize Azure Stack Hub’s network, improve efficiency, and manage the range of internal IP addresses effectively.
What factors need to be considered when recommending a public and internal IP strategy in Azure Stack Hub?
Factors to consider include the security requirements, the nature of the workload, the need for internet accessibility, the network performance and the operational costs.
What are the security implications when choosing between public and internal IP strategy in Azure Stack Hub?
Public IP strategy exposes Azure resources to the public internet, which can make them more susceptible to attacks. Conversely, an internal IP strategy provides an added layer of security as these IPs are not exposed to the public internet.
How can you secure a public IP address in Azure Stack Hub?
You can secure a public IP address by implementing security measures such as Azure Firewall, Network security groups (NSGs) and Application security groups (ASGs) to restrict and control inbound and outbound traffic.
What is a reserved public IP address in Azure Stack Hub and how does it fit into a public IP strategy?
A reserved public IP address is a static public IP address that you can reserve for your azure resources. It guarantees that the assigned IP will not change even when the resource is stopped or restarted. This ensures consistency and reliability in a public IP strategy.
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