The answer is to provide DNS name resolution for resources within Azure virtual networks privately. This is correct because Azure Private DNS zones allow you to register and resolve custom domain names, like contoso.internal, for VMs and other resources inside a VNet without exposing those queries to the public internet or requiring you to deploy and manage your own DNS servers. On the AZ-900 exam, this concept tests your understanding of how Azure enables private network communication—a core pillar of secure cloud architecture. A common trap is confusing Private DNS zones with Azure Public DNS or Azure Firewall’s DNS proxy; remember that Private DNS zones are strictly for internal name resolution within your virtual network boundary. Memory tip: think “Private = Internal, no internet exit.”
AZ-900 Describe Azure architecture and services Practice Question
This AZ-900 practice question tests your understanding of describe azure architecture and services. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
To provide DNS name resolution for resources within Azure virtual networks privately
Azure Private DNS zones provide DNS name resolution within a virtual network without requiring a custom DNS solution. They allow you to use your own domain names (e.g., contoso.internal) and automatically resolve them for resources inside the VNet, ensuring that DNS queries never leave the Azure network boundary. This is correct because the primary purpose is private, internal resolution, not public hosting or security filtering.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
To host public-facing domain names and DNS records
Why it's wrong here
Public DNS hosting is done by Azure DNS (public zones); Private DNS zones are for VNet-internal resolution.
✓
To provide DNS name resolution for resources within Azure virtual networks privately
Why this is correct
Private DNS zones resolve hostnames to private IPs within VNets without exposing records publicly.
Related concept
Read the scenario before looking for a memorised answer.
✗
To filter DNS requests for potentially malicious domains
Why it's wrong here
Malicious domain filtering is done by Azure FirewallDNS proxy with threat intelligence; Private DNS zones handle resolution.
✗
To translate domain names for cross-region traffic routing
Why it's wrong here
Cross-region routing uses Azure Traffic Manager or Front Door; Private DNS handles VNet-internal resolution.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse Azure Private DNS zones with public DNS zones or security services, assuming that 'private' implies security filtering or that DNS zones are always public-facing, when in fact Private DNS zones are purely for internal name resolution within Azure virtual networks.
Detailed technical explanation
How to think about this question
Azure Private DNS zones use the same DNS protocol (RFC 1035) but are scoped to a virtual network via a 'virtual network link' that registers DNS records automatically for resources like VMs using the Azure-provided DNS resolver (168.63.129.16). A subtle behavior is that you can enable auto-registration, which dynamically creates A records for VMs based on their private IP addresses, but this only works if the VNet is linked with the 'registration enabled' flag. In a real-world scenario, a microservices application deployed across multiple subnets can use a private zone like 'app.internal' to resolve service endpoints without exposing them to the internet.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A healthcare organisation deploys an application with a public-facing web tier and a private database tier. The database subnet has no public IP and only accepts connections from the web tier's security group. Questions like this test whether you can design cloud network isolation using VNets/VPCs, subnets, and security group rules.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this AZ-900 question in full detail.
Describe Azure architecture and services — This question tests Describe Azure architecture and services — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: To provide DNS name resolution for resources within Azure virtual networks privately — Azure Private DNS zones provide DNS name resolution within a virtual network without requiring a custom DNS solution. They allow you to use your own domain names (e.g., contoso.internal) and automatically resolve them for resources inside the VNet, ensuring that DNS queries never leave the Azure network boundary. This is correct because the primary purpose is private, internal resolution, not public hosting or security filtering.
What should I do if I get this AZ-900 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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