Custom domains in Supabase - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding Custom Domain Setup in Supabase

Which of the following best describes the first step to configure a custom domain for your Supabase project?

A Add your custom domain in the Supabase dashboard and then update your DNS provider with the provided CNAME or A record.

B Directly update your DNS provider with your Supabase project URL without adding the domain in Supabase dashboard.

C Create a new Supabase project with the custom domain name as the project name.

D Configure SSL certificates manually on your local machine before adding the domain.

💡 Hint

Think about what needs to be done both in Supabase and your DNS provider to link your domain.

To use a custom domain, you must first add it in the Supabase dashboard. Supabase then provides DNS records you must add to your DNS provider to point your domain to Supabase.

❓ Configuration

intermediate

DNS Record Type for Custom Domain in Supabase

You want to point your custom domain app.example.com to your Supabase project. Which DNS record type should you use to correctly configure this?

A Create a TXT record with your Supabase project ID.

B Create an A record pointing <code>app.example.com</code> to <code>8.8.8.8</code>.

C Create a CNAME record pointing <code>app.example.com</code> to <code>project-ref.supabase.co</code>.

D Create an MX record pointing <code>app.example.com</code> to <code>mail.supabase.co</code>.

💡 Hint

Think about which DNS record type points a subdomain to another domain.

A CNAME record maps a subdomain to another domain name, which is required to point your custom domain to your Supabase project URL.

❓ Architecture

advanced

SSL Certificate Management for Custom Domains in Supabase

When you add a custom domain to your Supabase project, how is SSL (HTTPS) handled to secure your domain?

A You must manually upload your SSL certificate and private key in the Supabase dashboard.

B Supabase automatically provisions and renews SSL certificates for your custom domain using Let's Encrypt.

C SSL is not supported for custom domains; you must use HTTP only.

D You need to purchase an SSL certificate from a third party and configure it on your DNS provider.

💡 Hint

Consider how modern cloud services simplify HTTPS setup for custom domains.

Supabase uses Let's Encrypt to automatically create and renew SSL certificates for your custom domains, so you don't have to manage certificates manually.

❓ service_behavior

advanced

Behavior of Supabase Custom Domain After DNS Propagation Delay

After adding your custom domain and updating DNS records, you notice your domain is not immediately accessible. What is the expected behavior during this period?

A Your domain may not resolve or may show the old site until DNS changes propagate globally, which can take up to 48 hours.

B Your domain will instantly redirect to your Supabase project URL without delay.

C Supabase disables your project until DNS propagation completes.

D You must restart your Supabase project to activate the custom domain.

💡 Hint

Think about how DNS changes work on the internet.

DNS changes take time to spread across the internet. During this time, your domain may not resolve correctly or may show cached content until propagation finishes.

❓ security

expert

Security Best Practice for Custom Domain DNS Configuration in Supabase

Which DNS configuration practice enhances security when setting up a custom domain for your Supabase project?

A Share your DNS provider credentials with your development team for faster updates.

B Use a wildcard CNAME record pointing all subdomains to Supabase without restrictions.

C Disable HTTPS to avoid SSL certificate errors during setup.

D Use DNSSEC (Domain Name System Security Extensions) to protect your DNS records from tampering.

💡 Hint

Consider how to protect DNS records from being altered by attackers.

DNSSEC adds a layer of security by digitally signing DNS records, preventing attackers from redirecting your domain to malicious sites.

Practice

1. What is the main purpose of setting a custom domain in Supabase?

easy

A. To enable faster query execution

B. To increase database storage capacity

C. To create multiple user accounts automatically

D. To use your own website address instead of a default Supabase URL

Solution

1. Step 1: Understand what a custom domain is

   A custom domain lets you use your own website address instead of a generic one provided by a service.

2. Step 2: Relate to Supabase usage

   In Supabase, setting a custom domain means your app uses your own URL, making it look professional and branded.

3. Final Answer:

   To use your own website address instead of a default Supabase URL -> Option D

4. Quick Check:

   Custom domain = Own website address [OK]

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

Common Mistakes:

• Thinking it increases database size
• Confusing with performance features
• Assuming it creates user accounts

2. Which DNS record type must you add to point your custom domain to Supabase?

easy

A. CNAME record

B. MX record

C. TXT record

D. SRV record

Solution

1. Step 1: Identify DNS record types for domain pointing

   CNAME records are used to alias one domain name to another, commonly used to point custom domains to services.

2. Step 2: Match with Supabase custom domain setup

   Supabase requires a CNAME record to link your custom domain to their servers.

3. Final Answer:

   CNAME record -> Option A

4. Quick Check:

   Custom domain pointing uses CNAME [OK]

Hint: Use CNAME to point domain to Supabase [OK]

Common Mistakes:

• Using MX record which is for email
• Using TXT record meant for verification
• Confusing SRV record with domain pointing

3. Given this Supabase custom domain setup snippet:

domain: "app.example.com"
records: [
  { type: "CNAME", value: "db.supabase.co" }
]

What happens when a user visits app.example.com?

medium

A. They are redirected to the Supabase database interface

B. Their browser connects to Supabase hosting for the app

C. They get an email verification prompt

D. They see a DNS error because CNAME is incorrect

Solution

1. Step 1: Understand CNAME effect

   The CNAME record points the domain to Supabase's hosting address, so requests go there.

2. Step 2: Interpret user visit behavior

   When visiting app.example.com, the browser connects to Supabase hosting serving the app, not the database interface or errors.

3. Final Answer:

   Their browser connects to Supabase hosting for the app -> Option B

4. Quick Check:

   CNAME directs browser to Supabase hosting [OK]

Hint: CNAME points domain to hosting, not email or errors [OK]

Common Mistakes:

• Confusing database interface with hosting
• Assuming DNS error from correct CNAME
• Thinking email verification appears on visit

4. You set a custom domain in Supabase but get a security warning in browsers. What is the most likely cause?

medium

A. You did not add an MX record

B. You used an invalid domain name format

C. You forgot to enable SSL for the custom domain

D. You set the CNAME to the wrong IP address

Solution

1. Step 1: Identify cause of browser security warnings

   Security warnings usually happen when SSL (secure connection) is missing or invalid.

2. Step 2: Relate to Supabase custom domain setup

   Supabase requires enabling SSL for custom domains to avoid browser warnings.

3. Final Answer:

   You forgot to enable SSL for the custom domain -> Option C

4. Quick Check:

   Missing SSL causes browser security warnings [OK]

Hint: Always enable SSL for custom domains [OK]

Common Mistakes:

• Confusing MX record with SSL
• Thinking domain format causes security warning
• Assuming CNAME IP address is used instead of hostname

5. You want to set up a custom domain dashboard.myapp.com for your Supabase project. Which steps must you follow to ensure it works correctly and securely?

hard

A. Buy the domain, add a CNAME DNS record pointing to Supabase, then enable SSL in Supabase settings

B. Buy the domain, add an MX record pointing to Supabase, then enable SSL in Supabase settings

C. Buy the domain, add a TXT record for verification, then disable SSL to avoid errors

D. Buy the domain, add an A record pointing to Supabase IP, then skip SSL setup

Solution

1. Step 1: Purchase domain and configure DNS

   First, buy your domain (dashboard.myapp.com) and add a CNAME record pointing to Supabase's domain to route traffic correctly.

2. Step 2: Enable SSL for secure connections

   Then, enable SSL in Supabase settings to secure the connection and avoid browser warnings.

3. Final Answer:

   Buy the domain, add a CNAME DNS record pointing to Supabase, then enable SSL in Supabase settings -> Option A

4. Quick Check:

   Domain + CNAME + SSL = Correct setup [OK]

Hint: Domain + CNAME + SSL = working custom domain [OK]

Common Mistakes:

• Using MX or TXT records incorrectly
• Skipping SSL causing security warnings
• Using A record instead of CNAME for Supabase