Wildcard vs SAN SSL: What Is an SSL Wildcard vs Multi-Domain (SAN) Certificate?

When it comes to securing your website and protecting your users’ data, choosing the right SSL certificate is one of the most important decisions you can make. Two of the most popular options for businesses managing multiple domains or subdomains are the SSL Wildcard certificate and the Multi-Domain SAN (Subject Alternative Name) certificate. Understanding the difference between these two types can save you time, money, and a great deal of technical headache. In this guide, we break down the wildcard vs SAN SSL debate so you can make the right choice for your organisation.

What Is an SSL Certificate?

Before diving into the specifics, it helps to understand what an SSL certificate actually does. SSL (Secure Sockets Layer) certificates are small digital files that authenticate the identity of a website and enable an encrypted connection between a web server and a browser. When a site has a valid SSL certificate, visitors see the padlock icon in their browser’s address bar, signalling that their connection is secure.

For businesses operating across multiple subdomains or entirely separate domains, a single standard SSL certificate simply won’t do. That’s where Wildcard and SAN certificates come in.

What Is a Wildcard SSL Certificate?

A Wildcard SSL certificate is designed to secure a single domain and all of its subdomains at one level of depth. The asterisk (*) in the certificate name acts as a wildcard character, meaning it can match any subdomain prefix.

For example, a Wildcard certificate issued for *.yourdomain.co.uk would automatically cover:

• www.yourdomain.co.uk
• mail.yourdomain.co.uk
• shop.yourdomain.co.uk
• blog.yourdomain.co.uk

However, it would not cover deeper subdomain levels such as store.shop.yourdomain.co.uk. For that, you would need a separate Wildcard certificate or a different solution altogether.

When Should You Use a Wildcard SSL Certificate?

A Wildcard certificate is an excellent choice if your business runs numerous subdomains under a single root domain. It is particularly popular amongst organisations that host client portals, regional microsites, or separate service areas all under one primary domain. The key advantage is simplicity — one certificate covers an unlimited number of subdomains, making management far more straightforward.

Pros of Wildcard SSL Certificates

• Cost-effective: Covering unlimited subdomains under one certificate is far cheaper than purchasing individual certificates for each subdomain.
• Easy management: Only one certificate needs to be renewed and managed.
• Scalable: New subdomains are automatically covered without requiring any certificate changes.
• Widely supported: Wildcard certificates are compatible with virtually all modern browsers and servers.

Cons of Wildcard SSL Certificates

• Single domain only: A Wildcard certificate cannot cover entirely separate domains.
• Security risk: If the private key is compromised, all subdomains are at risk simultaneously.
• Limited depth: Only one level of subdomain is covered.

What Is a Multi-Domain (SAN) SSL Certificate?

A Multi-Domain SSL certificate, also known as a SAN (Subject Alternative Name) certificate or Unified Communications Certificate (UCC), allows you to secure multiple fully qualified domain names (FQDNs) under a single certificate. Rather than using a wildcard character, each domain or subdomain is explicitly listed within the certificate’s SAN field.

For example, a single SAN certificate could cover:

• yourdomain.co.uk
• yourdomain.com
• anotherdomain.org.uk
• shop.thirddomain.co.uk

Most SAN certificates start with a base number of domains (often five) and allow you to add more as needed, usually up to 100 or 250 depending on the certificate authority.

When Should You Use a SAN SSL Certificate?

A SAN certificate is the ideal solution for businesses that manage multiple, entirely separate domains. Digital agencies, e-commerce businesses with multiple branded storefronts, or organisations with both a .co.uk and a .com presence will benefit greatly from a SAN certificate. It is also a popular choice for Microsoft Exchange and Office Communications Server environments.

Pros of Multi-Domain SAN SSL Certificates

• Covers multiple domains: Unlike Wildcard certificates, SAN certificates can secure completely different domain names.
• Centralised management: Manage a portfolio of domains under a single certificate renewal cycle.
• Flexible: You can add or remove domains from the certificate as your needs change (subject to reissuance).
• Cost savings: Cheaper than buying individual SSL certificates for each domain.

Cons of Multi-Domain SAN SSL Certificates

• Higher base cost: SAN certificates tend to be more expensive than standard or Wildcard certificates.
• Reissuance required: Adding or removing domains requires the certificate to be reissued, which can cause brief downtime.
• Domain exposure: All domains listed in the SAN field are publicly visible, which may not be ideal for sensitive internal domains.

Wildcard vs SAN SSL: Key Differences at a Glance

To help you make a more informed decision, here is a clear comparison of the two certificate types:

Feature	Wildcard SSL	SAN SSL
Covers subdomains	Yes (one level)	Yes (explicitly listed)
Covers multiple domains	No	Yes
Unlimited subdomains	Yes	No (listed individually)
Scalability	High (for subdomains)	Moderate (reissuance needed)
Cost	Moderate	Higher
Best for	Single domain with many subdomains	Multiple separate domains

Can You Combine Wildcard and SAN Certificates?

Yes — and in many cases, this is the most powerful solution available. Some certificate authorities offer Multi-Domain Wildcard certificates, which combine the features of both. These certificates allow you to secure multiple root domains, each with their own wildcard subdomain coverage. For larger enterprises or agencies managing complex digital infrastructure, this hybrid approach can be extremely cost-effective and efficient.

Which Certificate Is Right for Your Business?

The answer to the wildcard vs SAN SSL question ultimately depends on your specific requirements:

• If you run a single domain with many subdomains and expect that number to grow, a Wildcard SSL certificate is almost certainly your best bet.
• If you manage several distinct domains — whether for different brands, regions, or services — a SAN SSL certificate will give you the flexibility you need.
• If you need both, consider a Multi-Domain Wildcard certificate for comprehensive coverage.

For more in-depth guidance on managing your digital assets and SSL strategy, visit the DA Manager Blog, where you’ll find expert advice on domain management and web security best practices.

Final Thoughts

Choosing between a Wildcard and a SAN SSL certificate is not a one-size-fits-all decision. Both options offer significant advantages over purchasing multiple individual certificates, and both contribute to a more secure and trustworthy online presence. By carefully assessing the number and nature of the domains and subdomains you need to protect, you can select the certificate that offers the best balance of security, cost, and ease of management.

Whether you are a small business owner managing a growing web presence or an IT manager overseeing a complex multi-domain infrastructure, understanding the wildcard vs SAN SSL distinction is a crucial step towards building a robust and reliable security strategy for your organisation.