Wildcard DNS Records: Use Cases and Configuration

Introduction

A wildcard DNS record allows many undefined subdomains to resolve using one DNS rule. For example, a wildcard record for *.example.com can send unknown subdomains like client1.example.com or anything.example.com to the same destination.

Wildcard DNS can be useful for SaaS platforms, client portals, temporary environments and multi-tenant applications. But it should be used carefully. DNS can point wildcard subdomains to a server, but the server, application, CDN or hosting platform must still be configured to handle those hostnames.

Quick answer

What is wildcard DNS?

A wildcard DNS record is a DNS record that matches undefined subdomains under a domain.

*.example.com → 192.0.2.10

This means that random.example.com, client1.example.com or test.example.com may resolve to the same destination if no more specific DNS record exists.

Wildcard DNS usually applies only when there is no exact record for that subdomain. Exact records normally take priority.

How wildcard DNS works

Wildcard DNS acts as a fallback for subdomains that do not have their own records.

Specific record:
app.example.com A 192.0.2.20

Wildcard record:
*.example.com A 192.0.2.10

Result:
app.example.com uses 192.0.2.20 because it has a specific record.
anything.example.com uses 192.0.2.10 because it matches the wildcard.

The exact behavior can depend on DNS provider and record type, but specific records should be configured intentionally when they need different behavior.

Common use cases

Which records can be wildcard?

Most website wildcard setups use A, AAAA or CNAME records.

Why this matters

Wildcard DNS should be paired with proper application routing, SSL coverage, logging and security controls.

How to check wildcard DNS

Use DNS Lookup to test a subdomain that should only exist because of the wildcard record.

Common problems

How to configure it safely

1. Confirm the use case

   Decide why wildcard DNS is needed. Use it for dynamic subdomains, SaaS routing or multi-tenant applications, not as a replacement for planning.

2. Choose the correct record type

   Use A/AAAA if the wildcard should point to IP addresses. Use CNAME if the provider gives a hostname target.

3. Add the wildcard record

   Create a record for *.example.com at the active DNS provider.

4. Keep important subdomains explicit

   Add specific records for important hostnames such as www, mail, app, panel or shop if they need different behavior.

5. Configure the destination service

   Make sure the web server, CDN or application accepts wildcard hostnames.

6. Check SSL coverage

   Use a wildcard certificate or provider-managed SSL that covers the wildcard hostnames.

7. Test random and specific subdomains

   Check both a random wildcard subdomain and important explicit subdomains.

Wildcard DNS examples

Wildcard A record:
*.example.com.      300   IN   A       192.0.2.10

Wildcard CNAME record:
*.example.com.      300   IN   CNAME   app.hostingprovider.example.

Specific record taking priority:
app.example.com.    300   IN   A       192.0.2.20

dig random.example.com A
dig app.example.com A
dig '*.example.com' A

Wildcard DNS and SSL

Wildcard DNS and wildcard SSL are related but not the same. Wildcard DNS controls how subdomains resolve. Wildcard SSL controls whether HTTPS is valid for matching subdomains.

*.example.com DNS can point subdomains to a server.
*.example.com SSL certificate can secure many subdomains over HTTPS.

A wildcard certificate usually covers one subdomain level, such as app.example.com, but not deep names like dev.app.example.com unless specifically supported.

• SSL Checker →
• CAA Record Checker →
• Website Status Checker →

When not to use wildcard DNS

Avoid wildcard DNS when explicit records are clearer or safer.

Wildcard DNS may not be the best choice when:

• you only have a few known subdomains
• each subdomain points to a different service
• email-related hostnames need strict control
• unknown subdomains should fail instead of resolving
• SSL is not ready for wildcard hostnames
• your application cannot safely handle arbitrary hostnames

For many small websites, explicit DNS records are easier to manage.

Frequently asked questions