Multi-Domain vs Wildcard SSL Certificates: Differences & Uses

SSL certificates specifically are used to authenticate the identity of a website and secure data communications. A standard single-domain SSL certificate validates a single domain, often supporting both the www and non-www versions, and serves the two aforementioned functions.

This is not the only option available, however. Among the most convenient approaches, especially for larger organizations, are multi-domain and wildcard SSL certificates. These variations provide powerful opportunities to secure multiple domains and/or subdomains. Keep reading to learn more about these two types of SSL certificates, how they differ, and how they can benefit organizations with complex domain or infrastructure needs.

What is a Multi-domain SSL certificate?

Multi-domain SSL certificates serve the same functions as other SSL (Secure Sockets Layer) certificates: to encrypt data transmitted between browsers and servers while also authenticating website identities. This is typically accomplished through strict Certificate Authority verification processes. Multi-domain certificates make it possible to secure multiple domains — so long as they have the same owner. One certificate can secure up to 250 domains, including completely separate primary domains and the subdomains of a primary domain.

This type of certificate is sometimes referred to as Unified Communications Certificates (UCC) or Subject Alternative Name (SAN) certificates. SAN references a specific field within the certificate, with the X.509 standard incorporating a SAN extension to allow domain names to be associated with the certificate's subject.

As with single-domain setups, it is possible to select from multiple levels of validation when obtaining multi-domain certificates. Options include Extended Validation (EV), Organization Validation (OV), and Domain Validation (DV), with an EV SSL certificate representing the highest standard of validation — and DV the lowest.

What is a Wildcard SSL certificate?

In many respects, wildcard SSL certificates mimic their multi-domain counterparts by sharing the same primary purpose of delivering high-level encryption and authentication. However, the scope of their coverage differs dramatically, with wildcard certificates covering a single domain and subdomains under the primary domain.

With just one wildcard certificate, organizations can secure an unlimited number of subdomains under the primary domain. To illustrate this type of SSL, consider multiple subdomains (such as www.example.com, store.example.com, blog.example.com, reviews.example.com) and the base domain itself all secured using a single certificate.

Though the base domain is typically included and added as a separate SAN entry, this is not always the case. It’s also worth noting that only one level of subdomains are covered with a wildcard certificate, so a certificate for *.example.com does not cover www.store.example.com.

Differences between Multi-domain and Wildcard SSL certificates

Multi-domain and wildcard SSL certificates hold several similarities, including a broader level of protection than single-domain SSL certificates can achieve. Both approaches can streamline certificate management processes by ensuring that multiple subdomains (or, in some situations, different domains) are covered. These approaches also have the power to simplify certificate renewal processes by limiting how many certificates need to be renewed.

The main difference comes down to securing various domains and subdomains: as its name implies, multiple primary domains can be secured with multi-domain certificates while wildcard certificates are more limited in scope and can only secure one primary domain along with multiple subdomains.

However, multi-domain SSL certificates can cover wildcard domains, enabling them to secure multiple domains and their subdomains within a single certificate. This hybrid approach combines the flexibility of multi-domain certificates with the comprehensive coverage of wildcard certificates.

These core distinctions have ripple effects, influencing primary use cases and the types of organizations that seek out various certificates. In general, larger retailers are more likely to invest in multi-domain certificates to seamlessly handle far-reaching domain portfolios. Meanwhile, wildcard certificates appeal to smaller retailers—particularly those with single domains that also possess multiple subdomains.

Multi-domain SSL use cases

Many retailers maintain multiple domains to target customers in various regions or segment their product offerings. No matter the reason, these retailers need the comprehensive protection that multi-domain SSL certificates are best positioned to provide. Retailers opting for multi-domain solutions often fall into these use cases:

• Securing multiple hostnames or domains

Many of today's top retailers maintain complex domain portfolios that call for maximum flexibility and scalability. Often, this necessitates the securing of several hostnames. This can be achieved at scale (and for a reasonable cost) by implementing multi-domain SSL certificates.

• Using one certificate on multiple servers

Many retailers prioritize convenience when developing SSL certificate strategies. Under a multi-domain approach, a single certificate can be used even when multiple servers are used across various domains or subdomains. This ensures consistency in encryption and authentication while also streamlining certificate management.

• Securing mail servers with multiple domains

Email infrastructure can present unique concerns from a cryptographic perspective, but multi-domain certificates ensure integrity and confidentiality for complex mail servers.

After all, SSL encryption is crucial for safeguarding sensitive information that passes between mail servers and clients — but the risk of interception can be reduced when a comprehensive certificate solution is implemented. Multi-domain certificates provide a cost-effective and secure solution to organizations with significant email infrastructure complexities.

• Securing multiple internal server names

Internal server names are used within private networks to promote efficient management and maintenance of critical infrastructure. This approach is highly scalable and therefore represents a common strategy among retailers with diverse operations, multiple branches, or specialized services. Using a multi-domain certificate approach, several of these internal server names can be secured under a single certificate. However, the organization must still own the domain being used as if it was public.

Wildcard SSL use cases

Wildcard SSL certificates are generally favored by small to midsize retailers or other organizations that need to secure numerous subdomains. They provide a viable middle ground between single and multi-domain certificates. Wildcard certificates provide greater flexibility and scalability than single-domain solutions but tend to be more cost-effective than their multi-domain counterparts. Use cases worth considering include:

• Securing an unlimited number of subdomains

One of the main advantages of the wildcard approach? These certificates are capable of securing as many subdomains as required. This can make a world of difference for some retailers, as their websites may call for numerous subdomains.

• Securing domains and subdomains on different servers

Some organizations may need to set up domains and subdomains on separate servers. Often, this is done for purposes of resource allocation or to boost scalability. Wildcard SSL certificates allow for the domain and subdomains to be secured even when separate servers are required.

• Dynamic environments

Many organizations have complex website needs involving a consistent demand for subdomains that are not static or predefined but rather created dynamically according to evolving circumstances. In these situations, the importance of unlimited subdomain certificate coverage cannot be overstated.

• Increasing business productivity and efficiency

Easy and convenient to set up, wildcard certificates streamline key processes such as provisioning and installing. Along the way, this approach enhances flexibility, with subdomains easily added as required. This can limit the burden on already busy IT and web development teams, allowing them to instead shift their focus to other important matters.

• Cost-saving scenarios

Individual SSL certificates have a powerful role to play in securing websites, but cost-effective solutions may be needed when a higher volume of certificates is required. This is when a wildcard approach proves valuable, as it ensures unlimited coverage of subdomains at a lower unit cost.

Trust Sectigo for all your Multi-domain and Wildcard SSL certificate needs

Every type of digital certificate has unique qualities and unique use cases. Sectigo offers a comprehensive lineup, complete with several types of SSL/TLS certificates — including multi-domain and wildcard certificates.

Multi-domain and wildcard SSL certificates can be helpful for avoiding the added costs and commitments that come with separate SSL certificates, but it is important to examine multiple solutions before selecting an approach that aligns with key objectives.

Shop our SSL certificates today or learn more about Sectigo Certificate Manager to help with complex certificate lifecycle management needs.