Wildcard DNS Use Cases: When and Why to Use Them

What Is a Wildcard DNS Record?

A wildcard DNS record uses an asterisk (*) to match any subdomain that doesn't have its own specific record. If you create a wildcard A record for *.yourbrand.com, then anything.yourbrand.com, test.yourbrand.com, and randomword.yourbrand.com all resolve to the same IP address.

How Wildcard DNS Works

In DNS, records are matched from most specific to least specific:

1. Exact match first: If blog.yourbrand.com has its own A record, DNS uses that
2. Wildcard fallback: If no exact match exists, the wildcard record applies
3. No match: If there's no wildcard and no exact record, the subdomain doesn't resolve

This means wildcard records act as a catch-all for undefined subdomains.

Practical Use Cases

Multi-Tenant SaaS Platforms

SaaS companies often give each customer a subdomain:

• customer1.yourapp.com
• customer2.yourapp.com
• customer3.yourapp.com

A wildcard DNS record lets you add new customers without creating individual DNS records for each one. Your application handles routing based on the subdomain.

Development and Staging Environments

Developers use wildcard DNS for testing:

• feature-login.dev.yourbrand.com
• bugfix-cart.dev.yourbrand.com

Any developer can create a new subdomain environment without DNS changes.

Personalized Landing Pages

Marketing campaigns can use dynamic subdomains:

• newyork.yourbrand.com
• chicago.yourbrand.com
• custom-campaign.yourbrand.com

The server serves different content based on the subdomain.

Catch-All for Typos

If visitors accidentally type wwww.yourbrand.com or ww.yourbrand.com, a wildcard record ensures they still reach your site (combined with server-side redirect logic).

Multi-Site WordPress

WordPress Multisite can use subdomains for individual sites within a network. A wildcard record enables this without manual DNS entries for each site.

How to Set Up Wildcard DNS

Step 1: Access Your DNS Manager

Log into your DNS provider (Cloudflare, your registrar, Route 53, etc.).

Step 2: Create the Record

Add a new record:

• Type: A (or CNAME)
• Name: * (just the asterisk)
• Value: Your server's IP address (for A) or target domain (for CNAME)
• TTL: Your preferred time-to-live

Step 3: Configure Your Server

Your web server needs to handle requests for any subdomain. In nginx:

server {
    server_name *.yourbrand.com;
    # routing logic here
}

In Apache, use ServerAlias:

ServerAlias *.yourbrand.com

Step 4: SSL for Wildcards

Standard SSL certificates only cover specific domains. For wildcard subdomains, you need a wildcard SSL certificate (*.yourbrand.com). Let's Encrypt supports wildcard certificates through DNS validation.

Risks and Considerations

Security Concerns

Wildcard records mean any subdomain resolves to your server. Attackers can use random subdomains for:

• Phishing (fake-login.yourbrand.com)
• Cookie theft across subdomains
• Search engine spam

Mitigate by configuring your server to reject unknown subdomains and by monitoring subdomain usage.

SEO Impact

Search engines can index random subdomains, creating duplicate content issues. Configure your server to return 404 for unexpected subdomains or redirect them to your main domain.

Email Implications

A wildcard MX record means email sent to any@anything.yourbrand.com gets delivered. This can invite spam. Only use wildcard MX if you have a specific need and strong spam filtering.

Wildcard vs. Individual Records

Use wildcard when:

• You need dynamic subdomain creation
• You're building a multi-tenant platform
• Managing individual records isn't practical

Use individual records when:

• You have a fixed number of subdomains
• You need different subdomains pointing to different servers
• Security is a primary concern

Your Wildcard DNS Checklist

• [ ] Use case identified and validated
• [ ] Wildcard A or CNAME record created
• [ ] Web server configured to handle wildcard subdomains
• [ ] Wildcard SSL certificate installed
• [ ] Unknown subdomains handled (404 or redirect)
• [ ] Monitoring set up for subdomain abuse
• [ ] SEO implications addressed

Before configuring advanced DNS, make sure you have the right domain. Use BrandScout to check availability and secure your brand's primary domain.