What is a Wildcard SSL Certificate: A Comprehensive Guide

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What Is Wildcard SSL Certificate

Cyberspace threats loom large, and safeguarding sensitive data has never been more critical. With digital attackers perpetually devising methods to breach websites and compromise information, the imperative for robust data security and privacy is undeniable.

Wildcard SSL certificates are favored by numerous businesses aiming to fortify both primary domains and their intricate network of subdomains under a single certificate. The financial burden and administrative overhead of managing individual certificates are significantly reduced by enabling the protection of multiple subdomains using a single certificate.

This scalability offers a streamlined approach that resonates with businesses managing diverse online assets. However, while these benefits glorify simplicity and convenience, there exists a caveat—one that warrants careful consideration.

What is a Wildcard Certificate in SSL Security?

Wildcard SSL certificates stand as a formidable defense, safeguarding both domains and their expansive network of subdomains. The concept behind these certificates is elegantly simple: by utilizing an asterisk and a period preceding the domain name, a blanket of protection is extended to all associated subdomains.

This ingenious use of wildcards finds its prominent application within Secure Sockets Layer (SSL) certificates, fortifying the walls of encryption. In contrast, while effective, the conventional SSL certificate confines its protective embrace solely to a singular domain like www.example.com. The wildcard certificate, denoted as *.example.com, transcends such limitations. It envelops an array of subdomains, including mail.example.com, vpn.example.com, and payment.example.com, among others.

In an era where businesses possess a multitude of interconnected subdomains, the need for Wildcard SSL certificates has become paramount. These certificates stand as stalwart guardians against the persistent threat of hackers and fraudsters.

With constantly evolving technology, the acquisition and installation of wildcard SSL certificates have emerged as crucial strategies for upholding security standards.

The efficacy of this approach lies in its ability to shield the primary domain and extend its protective aura to all subsidiary subdomains. As businesses navigate the intricate web of online operations, the wildcard SSL certificate shines as an indispensable armor, fending off potential breaches and preserving integrity digitally.

How Does It Work?

Wildcard SSL certificates emerge as a dynamic solution whereby the mechanics behind the Wildcard SSL certificate’s prowess lie in its capacity to extend protection far beyond the traditional boundaries of SSL encryption.

Unified Encryption Across Subdomains

At its core, a Wildcard SSL certificate operates as an SSL certificate with a distinct attribute—its ability to encompass multiple subdomains at a single level. This transformative capability comes to life when considering the structure of a URL, such as “https://subdomain.maindomain.com/somefolder/somepage.html.” In this scenario, the Wildcard SSL certificate takes center stage, efficiently encrypting the primary domain and all subdomains at that particular level.

Enhancing Subdomain Protection

Conventionally, an SSL certificate is tailored to safeguard a solitary subdomain. For instance, if your SSL certificate pertains to “www.maindomain.com,” it inherently excludes subdomain coverage like “blog.maindomain.com.” The game-changer here is the Wildcard SSL certificate, which demolishes these limitations. Its inclusive design enables the encryption of an extensive range of subdomains residing within the same domain level.

First-Level Subdomain Security

Consider subdomains like “mail.domain.com,” “login.domain.com,” and “dev.domain.com.” These represent prime first-level subdomains that can be secured seamlessly using a single Wildcard SSL certificate. The beauty of this lies in its boundless potential—there’s no imposed limit on the number of subdomains safeguarded by the certificate. The Wildcard SSL certificate shatters the confines of conventional SSL protection.

Recommended: What is a Standard Wildcard SSL Certificate?

Second-Level Subdomain and Beyond

Delving deeper, we encounter second-level subdomains such as “member.mail.domain.com,” “login.mail.domain.com,” and “dev.mail.domain.com.” While these demand an additional Wildcard certificate for encryption, the critical distinction lies in the necessity for securing subdomains not just at the second level but also at the first subdomain level. This nuanced approach underscores the strategic nature of Wildcard SSL certificate deployment.

Recommended: How to Use Wildcard SSL Certificate for Second-Level Subdomain?

Wildcard SSL certificates stand as the vanguard of holistic encryption in the expansive domain landscape, where subdomains proliferate. Their ability to traverse and secure diverse subdomains—both at the first and potentially second levels—defines a new era of uncompromising data protection.

Recommended: What is a Double Wildcard SSL Certificate?

integrity, user trust, and seamless operations. This certificate stands as a guardian, steeled by the wildcard character’s expansive coverage, ensuring that domains and their sprawling network of subdomains remain impenetrable to potential threats.

Understanding the Mechanics of Wildcard SSL Certificates: A Technical Insight

At the heart of the functionality of Wildcard SSL certificates lies a nuanced process that begins with the generation of a Certificate Signing Request (CSR).

This technical maneuver paves the way for comprehensive domain and subdomain security, underpinning the convenience and versatility of Wildcard SSL certificates. Here’s a breakdown of the setup process and how Wildcard SSL certificates operate:

CSR Generation

The foundation of Wildcard SSL certificates is laid by creating a Certificate Signing Request. Initiated by the entity seeking the certificate, this request is submitted to a trusted Certificate Authority (CA). Within the CSR, a crucial distinction emerges—the common name field is populated with “*.yourdomain.com,” signifying the intent to secure all subdomains under the specified domain.

Recommended: How to Create CSR for Wildcard SSL with OpenSSL Commands?

Common Name and Subject Alternative Name (SAN)

In conjunction with the asterisk (*) wildcard character, the common name field sets the stage for comprehensive subdomain coverage. However, the Subject Alternative Name (SAN) field imparts flexibility to the certificate. This field includes the core domain name itself, “yourdomain.com.” By doing so, the certificate can operate seamlessly without necessitating a subdomain—a feature that amplifies the certificate’s practicality.

Universal Subdomain Protection

The amalgamation of the asterisk (*) at the designated subdomain level and including the core domain in the SAN field contributes to the Wildcard SSL certificate’s all-encompassing protective scope. This dynamic pairing enables the certificate’s deployment across an unlimited spectrum of subdomains associated with the domain, instilling a sense of security and integrity.

Streamlined Implementation

Acquiring and implementing a Wildcard SSL certificate is a strategic maneuver. Once the certificate is procured, generating the CSR with precision is pivotal. The key lies in embedding the wildcard character (*) before the domain—specifically, in the format “*.domain.com.” This careful configuration ensures that the certificate can effectively safeguard a multitude of subdomains while maintaining compatibility and trust.

In essence, the functioning of Wildcard SSL certificates is rooted in the synergy between technical intricacies and strategic foresight. This systematic approach not only streamlines the process of securing numerous subdomains but also underscores Wildcard SSL certificates’ adaptability and scalability of web security.

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What is the Difference between an SSL certificate and a Wildcard SSL Certificate?

When it comes to the choice between a standard SSL certificate and a wildcard SSL certificate, clarity is critical. Let’s break down the fundamental differences in a concise manner:

Standard SSL Certificate – Securing a Single Domain

The Standard SSL certificate, a single-domain SSL certificate, is tailored to protect a sole domain name. This certificate type, such as “www.domain.com” or “domain.com,” focuses its encryption prowess on ensuring the secure transmission of data between user browsers and the designated website’s server. This formidable barrier thwarts potential interception by malicious entities, safeguarding sensitive information exchanged during user interactions.

Wildcard SSL Certificate – Elevating Subdomain Security

In contrast, the wildcard SSL certificate provides the bedrock of secure connections for your primary domain and goes above and beyond. The wildcard SSL’s uniqueness is its capability to encompass an expansive array of first-level subdomains. A simple asterisk—like “*.domain.com”—is appended to the Fully Qualified Domain Name field during issuance to procure this certificate. This ingenious maneuver extends the protective umbrella to cover unlimited subdomains alongside your primary domain.

Key Distinction and Pricing Consideration

It’s important to highlight the pivotal distinction between the two—standard SSL caters to a solitary domain, while wildcard SSL extends its reach to many subdomains. When venturing to choose between wildcard SSL and standard SSL certificates, pricing is essential to keep in mind. The wildcard SSL certificate often comes with a different price point than its standard counterpart, reflecting its expanded coverage.

So, the choice between standard SSL and wildcard SSL certificates boils down to the scope of coverage you require, be it the focused security of a single domain or the all-encompassing protection of a domain and its diverse array of subdomains. With this insight, the decision-making process becomes a streamlined journey toward fortifying your online presence with the appropriate level of security.

Recommended: Know the Technical Difference between Standard SSL and Wildcard SSL Certificates

Why Should You Use a Wildcard SSL?

The effectiveness of safeguarding sensitive data and ensuring seamless online interactions cannot be overstated. Amid this landscape, the Wildcard SSL certificate emerges as a pivotal instrument, addressing a crucial need with remarkable efficacy.

At its core, the Wildcard SSL certificate encapsulates the power of a single certificate equipped with a wildcard character (*) strategically placed within the domain name field. This ingenious placement signifies a pivotal shift in approach that enables the certificate to provide steadfast protection not just for the primary domain but for many associated subdomains.

The rationale behind deploying a Wildcard SSL certificate is underscored by its unparalleled versatility. Imagine a business owning a domain such as (domainname).com. With a Wildcard SSL certificate in play, the encompassing protection extends to numerous subdomains, exemplified by hosts like “www.(domainname).com,” “mail.(domainname).com,” and more. The wildcard character becomes a symbol of boundless security, offering a unified shield across diverse subdomains under the umbrella of a singular certificate.

A compelling illustration serves to underline the potency of the Wildcard SSL certificate: Imagine a door that unlocks not just a single room but an entire mansion filled with interconnected spaces. The Wildcard SSL certificate functions in much the same manner, offering not only robust encryption but also a streamlined approach to security management.

Benefits of Wildcard SSL for Business

Wildcard SSL certificates emerge as a dynamic solution offering many benefits that resonate particularly with businesses dealing with many subdomains. Let’s delve into the crucial advantages that make Wildcard SSL certificates an indispensable tool for data protection:


Individual SSL certificates can translate into substantial security expenses for enterprises navigating a complex web of subdomains. The wildcard subdomain certificate revolutionizes this by eliminating the need for multiple certificates. This cost-effective approach ensures that businesses can secure unlimited subdomains at the price of a single Wildcard SSL certificate. This economic advantage is appealing, especially for small and medium-sized businesses (SMBs) that strive to maintain data security within budget constraints.

Infinite Subdomain Security

The adaptability of Wildcard SSL certificates is exemplified by their ability to encompass an unlimited array of subdomains. As your organization expands its digital presence, new subdomains are automatically protected without necessitating additional renewals. This scalability showcases the efficacy of Wildcard SSL certificates in evolving alongside your business.

User Trust

A secured website carries intrinsic value in users’ eyes. The encryption provided by Wildcard SSL certificates instills confidence among visitors, leading to increased traffic and user trust. With domain or business validation options, these certificates authenticate the credibility of your website, reassuring users that a reputable certificate authority (CA) has deemed it secure for online transactions and interactions.

Search Engine Optimization (SEO) Boost

The ever-evolving landscape of SEO emphasizes website security. Google’s endorsement of SSL enabled websites as ranking-worthy entities enhances their visibility in search results. The power of SSL as a ranking signal underscores its importance in bolstering a website’s online presence.


Wildcard certificates exhibit remarkable compatibility with a wide range of servers and browsers, spanning desktop and mobile platforms. This high level of compatibility, often exceeding 99 percent, ensures a seamless browsing experience free from SSL warning disruptions. The absence of SSL encryption may even lead Google to label websites as insecure, further highlighting the need for comprehensive SSL coverage.

Instant Issuance and Simplified Management

The expeditious issuance process of Wildcard SSL certificates, often completed within two days following thorough verification, enhances operational efficiency. Subdomains are immediately incorporated into the certificate upon issuance. Moreover, the streamlined certificate management experience relieves the complexities of juggling multiple certificates. The single-click installation for numerous subdomains, along with simplified management of expiration, renewal, and reissues, reduces administrative burdens and expedites the safeguarding of websites.

If digital security, Wildcard SSL certificates transcend mere encryption; they embody a comprehensive strategy that addresses cost, scalability, user trust, SEO enhancement, compatibility, and management simplicity. Embracing these certificates equips businesses with a multifaceted shield, safeguarding sensitive data and the integrity of their online presence.

What are the Risks of a Wildcard SSL Certificate?

Wildcard SSL certificates offer an enticing blend of affordability and encryption coverage, yet they are not without their inherent limitations. While they present an economical solution for securing a vast array of subdomains, certain drawbacks warrant careful consideration, such as:

Extended Validation (EV) Gap

One notable limitation is the absence of extended validation (EV) level assurance in Wildcard SSL certificates. This omission curtails the ability to obtain the highest level of identity verification and validation, potentially impacting the overall trustworthiness of the certificate.

Subdomain Complexity

Securing second and third-level subdomains poses a challenge with Wildcard SSL certificates. The blanket coverage provided by the wildcard symbol (*) is confined to a single level of subdomains. This limitation can hinder efforts to secure more intricate subdomain structures.

Phishing Vulnerability

One of the most significant concerns is the susceptibility of Wildcard SSL certificates to phishing attacks. Malicious actors can exploit the trust associated with these certificates without meticulous control and vigilant monitoring. Hackers infiltrating a domain secured by a Wildcard certificate can exploit this privilege to create seemingly legitimate subdomains. This, in turn, can be leveraged for phishing campaigns, deceiving unsuspecting users into sharing sensitive information.

Compromised Privilege

The inherent architecture of Wildcard certificates can inadvertently grant hackers the capability to generate an unlimited number of subdomains under the umbrella of the certificate. This can result in a scenario where subdomains, seemingly endorsed by the Wildcard certificate, are manipulated for malicious purposes.

Private Key Sharing

Employing Wildcard certificates to secure multiple subdomains often necessitates sharing the private key among agents responsible for different subdomains. This practice introduces a heightened risk of compromise and unauthorized access, potentially undermining the security integrity of the certificate.

Compatibility Concerns

The wildcard character (*) might not be recognized by specific older mobile devices, rendering them incompatible with Wildcard SSL certificates. In such cases, acquiring individual certificates for compatibility becomes a requisite.

Can I Use My Wildcard SSL on Multiple Domains?

A Multi-Domain Wildcard Certificate presents a comprehensive solution that empowers users to secure multiple domains under a single certificate umbrella. The precise number of domains covered varies based on the vendor chosen for acquisition. Depending on the vendor’s offerings, this versatile certificate can span anywhere from securing up to 100 to 250 domains or potentially more.

Organizations can unlock an expansive horizon of secure web by the capabilities of both Multi-Domain and Wildcard SSL certificates. This strategic fusion mitigates the need for separate certificates for each domain, simplifying management and administration.

The Multi-Domain Wildcard Certificate harmonizes security and convenience, presenting a holistic approach that resonates with businesses managing an array of online assets.


The advent of Wildcard SSL certificates marks a pivotal juncture in the evolution of cutting-edge security. The ability to safeguard numerous domains, each with its array of subdomains, underscores the progressive nature of SSL certificate technology.

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Janki Mehta

Janki Mehta

Janki Mehta is a Cyber-Security Enthusiast who constantly updates herself with new advancements in the Web/Cyber Security niche. Along with theoretical knowledge, she also implements her practical expertise in day-to-day tasks and helps others to protect themselves from threats.