Azure DNS basics - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ service_behavior

intermediate

How does Azure DNS resolve domain names?

When a user types a domain name managed by Azure DNS, what happens behind the scenes to resolve the name to an IP address?

A Azure DNS responds directly with the IP address from its authoritative DNS zone records.

B Azure DNS queries the user's local DNS cache and returns the cached IP address.

C Azure DNS forwards the request to the domain registrar to get the IP address.

D Azure DNS redirects the request to a random Azure region to find the IP address.

💡 Hint

Think about what an authoritative DNS server does.

Azure DNS hosts authoritative DNS zones. When queried, it responds directly with the IP address from its stored DNS records without forwarding the request elsewhere.

❓ Configuration

intermediate

Which Azure resource is required to manage DNS zones?

To create and manage DNS zones in Azure, which resource must you create first?

A Azure Storage Account

B Azure Virtual Network

C Azure DNS Zone resource

D Azure App Service Plan

💡 Hint

Consider the resource that holds DNS records for a domain.

Azure DNS Zone is the resource that represents a DNS zone and contains DNS records for a domain.

❓ security

advanced

How to restrict who can update DNS records in Azure DNS?

You want to ensure only specific team members can update DNS records in your Azure DNS zone. What is the best way to enforce this?

A Enable Azure Firewall to filter DNS update requests.

B Assign Azure Role-Based Access Control (RBAC) roles scoped to the DNS zone resource.

C Use network security groups to block access to the DNS zone.

D Create a separate Azure subscription for DNS management.

💡 Hint

Think about Azure's built-in permission management system.

Azure RBAC allows you to assign permissions to users or groups scoped to specific resources like DNS zones, controlling who can update records.

❓ Architecture

advanced

What is the benefit of using Azure DNS private zones?

Why would you use Azure DNS private zones instead of public DNS zones?

A To manage DNS records accessible only within your Azure virtual networks.

B To make your DNS records publicly available on the internet.

C To automatically replicate DNS zones across all Azure regions.

D To enable DNS over HTTPS for all your domains.

💡 Hint

Consider internal network name resolution needs.

Azure DNS private zones allow you to create DNS zones that are only visible and resolvable within your Azure virtual networks, enhancing security and isolation.

✅ Best Practice

expert

What is the recommended way to ensure high availability of DNS resolution in Azure?

You want to design your DNS setup in Azure to avoid downtime and ensure fast resolution globally. Which approach follows best practices?

A Use Azure DNS with multiple DNS zones for the same domain in different subscriptions.

B Manually update DNS records daily to balance load across regions.

C Use a single Azure DNS zone and rely on local DNS caching only.

D Use Azure DNS public zones with Azure Traffic Manager to route traffic based on health and geography.

💡 Hint

Think about combining DNS with traffic routing services.

Azure Traffic Manager works with Azure DNS to route user requests to the healthiest and closest endpoints, improving availability and performance globally.

Practice

1. What is the main purpose of Azure DNS?

easy

A. To monitor network traffic in real-time

B. To store files and documents securely

C. To run virtual machines in the cloud

D. To manage domain names and translate them to IP addresses

Solution

1. Step 1: Understand Azure DNS role

   Azure DNS is used to manage domain names and their records inside Azure.

2. Step 2: Identify main function

   It translates domain names into IP addresses so users can find services on the internet.

3. Final Answer:

   To manage domain names and translate them to IP addresses -> Option D

4. Quick Check:

   Azure DNS = Domain name management [OK]

Hint: Azure DNS handles domain names, not files or VMs [OK]

Common Mistakes:

• Confusing DNS with storage services
• Thinking Azure DNS runs virtual machines
• Mixing DNS with network monitoring

2. Which of the following is the correct way to create a DNS zone in Azure CLI?

easy

A. az network dns zone create -g MyResourceGroup -n example.com

B. az dns create zone -g MyResourceGroup -n example.com

C. az network create dnszone -g MyResourceGroup -n example.com

D. az dns zone new -g MyResourceGroup -n example.com

Solution

1. Step 1: Recall Azure CLI syntax for DNS zone creation

   The correct command uses 'az network dns zone create' with resource group and zone name.

2. Step 2: Compare options

   Only az network dns zone create -g MyResourceGroup -n example.com matches the correct Azure CLI syntax for creating a DNS zone.

3. Final Answer:

   az network dns zone create -g MyResourceGroup -n example.com -> Option A

4. Quick Check:

   Correct Azure CLI DNS zone command = az network dns zone create -g MyResourceGroup -n example.com [OK]

Hint: Remember 'az network dns zone create' for DNS zones [OK]

Common Mistakes:

• Using incorrect command verbs like 'new' or 'create zone'
• Omitting 'network' in the command
• Mixing up command order or parameters

3. Given this Azure CLI command:
az network dns record-set a add-record -g MyRG -z example.com -n www -a 10.0.0.1
What does this command do?

medium

A. Creates a DNS zone named 'www' in resource group MyRG

B. Creates an A record named 'www' pointing to IP 10.0.0.1 in example.com zone

C. Deletes the A record named 'www' in example.com zone

D. Adds a CNAME record pointing 'www' to 10.0.0.1

Solution

1. Step 1: Analyze command components

   The command adds an A record ('-a') named 'www' with IP 10.0.0.1 to the DNS zone 'example.com' in resource group 'MyRG'.

2. Step 2: Confirm record type and action

   'add-record' means creating a record, and 'a' specifies an A record (IP address).

3. Final Answer:

   Creates an A record named 'www' pointing to IP 10.0.0.1 in example.com zone -> Option B

4. Quick Check:

   Command adds A record 'www' with IP 10.0.0.1 [OK]

Hint: A record = IP address, add-record means create [OK]

Common Mistakes:

• Confusing A record with CNAME
• Thinking the command deletes records
• Misreading '-n' as zone name instead of record name

4. You run this command to add a TXT record:
az network dns record-set txt add-record -g RG1 -z example.com -n info -v "verification=12345"
But it fails with an error. What is the likely cause?

medium

A. The '-v' parameter is invalid; it should be '-a' for TXT records

B. The record name '-n' cannot be 'info' for TXT records

C. The TXT record value must be enclosed in single quotes, not double quotes

D. The resource group name 'RG1' is missing

Solution

1. Step 1: Check TXT record syntax

   TXT record values often require single quotes to avoid shell parsing errors.

2. Step 2: Identify error cause

   Using double quotes can cause the shell to misinterpret the value, leading to failure.

3. Final Answer:

   The TXT record value must be enclosed in single quotes, not double quotes -> Option C

4. Quick Check:

   Use single quotes for TXT values to avoid errors [OK]

Hint: Use single quotes for TXT record values in CLI [OK]

Common Mistakes:

• Using wrong parameter '-a' instead of '-v' for TXT
• Assuming record name restrictions incorrectly
• Ignoring resource group existence

5. You want to create a DNS zone for your domain 'myapp.com' and add two records: an A record for 'app' pointing to 192.168.1.10 and a CNAME record for 'www' pointing to 'app.myapp.com'. Which sequence of Azure CLI commands correctly achieves this?

hard

A. 1) az network dns zone create -g RG -n myapp.com2) az network dns record-set a add-record -g RG -z myapp.com -n app -a 192.168.1.103) az network dns record-set cname set-record -g RG -z myapp.com -n www -c app.myapp.com

B. 1) az network dns zone create -g RG -n myapp.com2) az network dns record-set cname add-record -g RG -z myapp.com -n app -c 192.168.1.103) az network dns record-set a set-record -g RG -z myapp.com -n www -a app.myapp.com

C. 1) az dns zone create -g RG -n myapp.com2) az network dns record-set a add-record -g RG -z myapp.com -n app -a 192.168.1.103) az network dns record-set cname add-record -g RG -z myapp.com -n www -c app.myapp.com

D. 1) az network dns zone create -g RG -n myapp.com2) az network dns record-set a add-record -g RG -z myapp.com -n app -a 192.168.1.103) az network dns record-set cname add-record -g RG -z myapp.com -n www -a app.myapp.com

Solution

1. Step 1: Create DNS zone

   Use 'az network dns zone create' with resource group and domain name to create the zone.

2. Step 2: Add A record for 'app'

   Use 'az network dns record-set a add-record' with correct parameters to add IP address record.

3. Step 3: Add CNAME record for 'www'

   Use 'az network dns record-set cname set-record' to point 'www' to 'app.myapp.com'.

4. Final Answer:

   1) az network dns zone create -g RG -n myapp.com
   2) az network dns record-set a add-record -g RG -z myapp.com -n app -a 192.168.1.10
   3) az network dns record-set cname set-record -g RG -z myapp.com -n www -c app.myapp.com -> Option A

5. Quick Check:

   Zone create + A record + CNAME set-record = 1) az network dns zone create -g RG -n myapp.com
   2) az network dns record-set a add-record -g RG -z myapp.com -n app -a 192.168.1.10
   3) az network dns record-set cname set-record -g RG -z myapp.com -n www -c app.myapp.com [OK]

Hint: Use 'add-record' for A, 'set-record' for CNAME [OK]

Common Mistakes:

• Using wrong commands like 'az dns zone create'
• Mixing up 'add-record' and 'set-record' for CNAME
• Assigning IP to CNAME record