CDN with custom domains in Azure - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding Custom Domain Validation in Azure CDN

When adding a custom domain to an Azure CDN endpoint, what is the primary method Azure uses to verify domain ownership?

A Azure sends an email to the domain registrant to confirm ownership.

B Azure checks for a specific CNAME record pointing from the custom domain to the CDN endpoint.

C Azure requires uploading a verification file to the root directory of the website.

D Azure uses WHOIS database lookup to verify the domain owner.

💡 Hint

Think about how DNS records can prove control over a domain.

Azure validates custom domains by requiring a CNAME DNS record that points the custom domain to the CDN endpoint hostname. This proves control over the domain.

❓ Architecture

intermediate

Designing a CDN Setup with Multiple Custom Domains

You need to serve content via Azure CDN for three different custom domains: example.com, images.example.com, and videos.example.com. What is the best practice for configuring these domains in Azure CDN?

A Create one CDN endpoint and add all three custom domains to it after validation.

B Create three separate CDN endpoints, each with one custom domain assigned.

C Use one CDN endpoint with a wildcard custom domain covering all subdomains.

D Create one CDN endpoint and use URL rewriting rules to handle different domains.

💡 Hint

Consider how Azure CDN endpoints support multiple custom domains.

Azure CDN endpoints can have multiple custom domains added after validation. This allows serving multiple domains from a single endpoint efficiently.

❓ scaling

advanced

Handling SSL/TLS for Multiple Custom Domains on Azure CDN

You have configured multiple custom domains on a single Azure CDN endpoint. What is the recommended approach to enable HTTPS for all these domains with minimal management overhead?

A Use a wildcard SSL certificate covering all domains and upload it to Azure CDN.

B Manually upload individual SSL certificates for each custom domain and renew them yourself.

C Use Azure CDN managed certificates which automatically provision and renew SSL certificates for all custom domains.

D Disable HTTPS and serve content only over HTTP to avoid certificate management.

💡 Hint

Think about automation and ease of maintenance for SSL certificates.

Azure CDN offers managed certificates that automatically handle provisioning and renewal of SSL certificates for custom domains, reducing operational overhead.

❓ tradeoff

advanced

Choosing Between Azure CDN Standard and Premium for Custom Domains

Which tradeoff is true when deciding between Azure CDN Standard and Premium tiers for supporting custom domains with HTTPS?

A Premium tier supports custom domain HTTPS with managed certificates and advanced rules engine, but costs more than Standard.

B Standard tier supports unlimited custom domains with free SSL, Premium requires manual SSL management.

C Premium tier does not support custom domains, only Standard does.

D Standard tier supports managed HTTPS for custom domains and advanced rules engine at a lower cost than Premium.

💡 Hint

Consider feature differences and pricing between tiers.

Azure CDN Premium offers advanced features like managed HTTPS for custom domains and a powerful rules engine but at a higher price compared to Standard.

❓ estimation

expert

Estimating DNS Propagation Time Impact on Custom Domain Activation

After adding a custom domain with a CNAME record to an Azure CDN endpoint, what is the typical maximum time you should wait before the custom domain becomes active and accessible via HTTPS?

A Up to 1 week because SSL certificates require manual approval.

B Less than 5 minutes because Azure instantly validates DNS records.

C Exactly 24 hours as Azure enforces a fixed waiting period.

D Up to 48 hours due to DNS propagation delays and certificate issuance time.

💡 Hint

Think about real-world DNS propagation and automated certificate issuance.

DNS changes can take time to propagate globally, and Azure's managed certificate issuance also requires some time, so up to 48 hours is typical.

Practice

1. What is the primary purpose of using a custom domain with Azure CDN?

easy

A. To deliver content using your own website address instead of the default CDN URL

B. To increase the storage capacity of the CDN

C. To reduce the cost of CDN services

D. To disable HTTPS on the CDN endpoint

Solution

1. Step 1: Understand CDN default behavior

   Azure CDN provides a default URL for content delivery, but it uses a generic domain name.

2. Step 2: Purpose of custom domain

   Using a custom domain lets you serve content with your own website address, improving branding and user trust.

3. Final Answer:

   To deliver content using your own website address instead of the default CDN URL -> Option A

4. Quick Check:

   Custom domain = Own website address [OK]

Hint: Custom domain means your own website address on CDN [OK]

Common Mistakes:

• Thinking custom domain increases storage
• Assuming custom domain reduces cost
• Believing custom domain disables HTTPS

2. Which DNS record type must you create to map your custom domain to an Azure CDN endpoint?

easy

A. CNAME record

B. SRV record

C. TXT record

D. MX record

Solution

1. Step 1: Identify DNS record for domain aliasing

   CNAME records map one domain name to another, which is needed to point your custom domain to the CDN endpoint.

2. Step 2: Exclude other DNS record types

   MX is for mail, TXT for text info, SRV for service location, none suitable for domain aliasing.

3. Final Answer:

   CNAME record -> Option A

4. Quick Check:

   Custom domain uses CNAME DNS record [OK]

Hint: Custom domain points to CDN via CNAME record [OK]

Common Mistakes:

• Using MX record for domain mapping
• Confusing TXT record with CNAME
• Trying to use SRV record for CDN

3. Given the following Azure CLI command snippet to add a custom domain to a CDN endpoint, what will happen if the DNS CNAME record is not set correctly?

az cdn custom-domain create --endpoint-name myEndpoint --profile-name myProfile --resource-group myGroup --hostname www.example.com

medium

A. The custom domain will be added successfully without any issues

B. The CDN endpoint will automatically create the DNS record

C. The custom domain will be added but HTTPS will be disabled

D. The command will fail with a DNS validation error

Solution

1. Step 1: Understand DNS validation in Azure CDN

   Azure CDN requires DNS validation to confirm ownership of the custom domain via CNAME record.

2. Step 2: Effect of missing or incorrect DNS record

   If the CNAME record is missing or incorrect, the command fails with a DNS validation error to prevent misconfiguration.

3. Final Answer:

   The command will fail with a DNS validation error -> Option D

4. Quick Check:

   Missing CNAME causes DNS validation error [OK]

Hint: DNS must validate custom domain or command fails [OK]

Common Mistakes:

• Assuming CDN auto-creates DNS records
• Thinking custom domain adds without DNS setup
• Believing HTTPS disables if DNS is wrong

4. You added a custom domain to your Azure CDN endpoint but HTTPS is not working. Which of the following is the most likely cause?

medium

A. The CDN endpoint does not support HTTPS at all

B. You used an A record instead of a CNAME record in DNS

C. You forgot to enable HTTPS on the custom domain in the CDN settings

D. The CDN profile is in a different Azure region than your resource group

Solution

1. Step 1: Check HTTPS enablement for custom domain

   Azure CDN requires explicit enabling of HTTPS on custom domains to serve secure content.

2. Step 2: Exclude other causes

   CDN endpoints support HTTPS, A record usage causes DNS issues but not HTTPS directly, region mismatch does not block HTTPS.

3. Final Answer:

   You forgot to enable HTTPS on the custom domain in the CDN settings -> Option C

4. Quick Check:

   HTTPS must be enabled on custom domain [OK]

Hint: Enable HTTPS explicitly for custom domain [OK]

Common Mistakes:

• Assuming HTTPS is automatic
• Blaming region mismatch for HTTPS failure
• Using A record instead of CNAME but ignoring HTTPS setting

5. You want to design a scalable Azure CDN solution with a custom domain that supports HTTPS and handles millions of users globally. Which combination of steps is the best practice?

hard

A. Create a CDN profile only, add your custom domain with an A record, disable HTTPS to reduce latency, and rely on a single CDN POP

B. Create a CDN profile and endpoint, add your custom domain with a CNAME DNS record, enable HTTPS with Azure-managed certificates, and use multiple CDN POPs worldwide

C. Create multiple CDN profiles for each region, add custom domains without DNS changes, and enable HTTPS manually with self-signed certificates

D. Use Azure CDN without custom domains, enable HTTPS, and configure DNS to point directly to the origin server

Solution

1. Step 1: Setup CDN profile and endpoint with custom domain

   Create a CDN profile and endpoint, then add your custom domain using a CNAME DNS record for proper domain mapping.

2. Step 2: Enable HTTPS and use global CDN POPs

   Enable HTTPS using Azure-managed certificates for security and scalability, and leverage multiple CDN Points of Presence (POPs) worldwide to handle global traffic efficiently.

3. Final Answer:

   Create a CDN profile and endpoint, add your custom domain with a CNAME DNS record, enable HTTPS with Azure-managed certificates, and use multiple CDN POPs worldwide -> Option B

4. Quick Check:

   Custom domain + CNAME + HTTPS + global POPs = Best practice [OK]

Hint: Use CNAME, enable HTTPS, and leverage global CDN POPs [OK]

Common Mistakes:

• Using A record instead of CNAME
• Disabling HTTPS to save latency
• Skipping DNS changes for custom domains
• Relying on single CDN POP for global scale