Wildcard SSL Certificate
A Wildcard SSL certificate helps secure one or more subdomains on a single domain name with one SSL certificate. This makes it easier to deploy SSL on subdomains rather than having to purchase separate SSL certificates for each one. Wildcard SSL certificates are useful for websites with many subdomains that need to serve protected content over HTTPS.
In this article, we will comprehensively cover what a Wildcard SSL certificate is, how it works, the benefits it provides, things to consider before purchasing one, and more. By the end, you should have a clear understanding of why an organization may want to use a Wildcard SSL and how it can simplify website security.
Let’s begin with looking at the basic definition and purpose of a Wildcard SSL certificate.
What is a Wildcard SSL Certificate?
A Wildcard SSL certificate allows one SSL certificate to secure and authenticate multiple subdomains on a single domain by using a wildcard character (*) as a leftmost label of the domain name.
For example, a single Wildcard SSL certificate with the domain name *.example.com would secure:
- mail.example.com
- www.example.com
- login.example.com
- support.example.com
- anyothername.example.com
Essentially, any subdomain on example.com that comes before or instead of www can be secured with one Wildcard SSL certificate. This makes it much more convenient than having to purchase a separate SSL certificate for each subdomain.
Some key things to note about a Wildcard SSL certificate:
- It uses a “*” wildcard character to represent all possible subdomain variations that may exist now or in the future.
- It only works for subdomains, not the actual domain name itself (example.com in this case). You need a separate standard SSL for the domain.
- The certificate validity is domain-based, not hostname-based like subject alternative names (SAN) certificates.
- It’s a more cost-effective option than individual certificates if you frequently add/remove subdomains.
Why Use a Wildcard SSL Certificate?
There are several compelling benefits that motivate organizations to use a Wildcard SSL certificate rather than individual certificates:
Simplified Management
Administering one Wildcard SSL certificate for all subdomains is much simpler and less time-consuming than handling dozens of individual certificates. You save effort on ongoing management and renewal of certificates.
Future-Proofing
A Wildcard SSL certificate automatically secures any new subdomains added in the future without needing a new certificate. This future-proofs your implementation as your domain structure evolves.
Cost Savings
While more expensive initially than a single subdomain certificate, Wildcards work out to be cheaper long-term as you avoid purchasing certificates for each new subdomain. The savings compound over time.
Better Performance
Since all subdomains share one certificate, there is less latency compared to individually validating certificates on each subdomain request. This improves page load speeds.
SEO Benefits
Google gives an SEO ranking boost to websites that fully implement HTTPS via protocols like HSTS and CSP. Wildcards help achieve this across all subdomains.
Enhanced Security
Wildcards extend the security and trust benefits of SSL to protect all subdomains simultaneously. This reduces overall exposure from any single untrusted subdomain.
As this overview shows, the simplification, future-proofing and cost advantages of Wildcard SSL make it a smart choice for websites with numerous subdomains that need HTTPS secured. Let’s dig deeper into how they work.
How Does a Wildcard SSL Certificate Work?
The basic process of how a Wildcard SSL certificate works to secure multiple subdomains is:
- You purchase a Wildcard SSL certificate from a certificate authority (CA) like RapidSSL, DigiCert, Sectigo, GoDaddy, Comodo, or GeoTrust.
- The CA validates your ownership of the domain through methods like uploading a TXT record.
- Once verified, the CA issues a Wildcard SSL certificate with a common Name (CN) that includes the wildcard character (*).
- You install the Wildcard certificate onto your web server along with the intermediate and root certificates.
- When a client connects to any subdomain within the wildcard domain (e.g. mail.example.com), the certificate is presented.
- The client’s browser verifies that the CN matches the requested hostname using the wildcard, so it trusts the certificate is valid.
- An encrypted HTTPS communication channel is then established using the standard SSL/TLS handshake process.
- As long as the hostname is within the wildcard pattern, any subdomain will be automatically secured without further configuration needed.
How to Validate Wildcard SSL Certificates
It’s important for CAs to properly validate that an organization genuinely owns the domain range covered by a Wildcard SSL certificate request. This helps reduce the risk of certificates being misissued. Common validation steps include:
- Domain Control Validation: Proving control of the domain by uploading a TXT record with a random value to a DNS zone file.
- Organization Validation: Checking business incorporation records match the certificate applicant.
- Signature Validation: Requiring responsible corporate individuals to digitally sign validation documents.
- Financial Validation: Cross-checking payment information to bank records.
Once validated, the CA issues the Wildcard certificate which is then trusted by browsers visiting any matching subdomains secure via HTTPS. This validation process underpins the trust model that allows wildcard certificates to broadly secure multiple domains.
Things to Consider Before Buying
While Wildcard SSL certificates offer clear advantages, there are some things to carefully consider first:
- Intended Usage – Will you frequently add/remove subdomains long-term to justify the upfront wildcard cost?
- Subdomain Structure – Does your domain hierarchy lend itself well to being secured by a wildcard pattern?
- Cost Comparison – Run numbers to compare wildcard vs individual certificate costs over the intended usage period.
- Security Controls – Wildcards increase exposure if any subdomain is compromised versus individual certs.
- Future Plans – Could your domain structure or usage change in ways that make a wildcard no longer suitable?
- Technical Ability – Do you have the skills needed to properly configure and renew a wildcard certificate?
Proper evaluation upfront helps determine if a wildcard is indeed the most cost-effective and appropriate SSL solution for your website’s current and future needs compared to alternatives.
Wildcard SSL Certificate Types
When shopping for a Wildcard SSL certificate, you’ll find there are different types available depending on intended usage and validation requirements:
- Domain Validated (DV) – The basic Wildcard type. Validates domain ownership through methods like files uploaded to the domain. Not suitable for EV indicators.
- Organization Validated (OV) – Offers increased levels of organization identity validation over DV. May be required for specific browser trust programs.
- Internal Wildcard – Meant for securing internal servers not exposed to the public internet. Subject to lighter validation processes.
- Multi-Domain Wildcard – Allows securing multiple explicit second-level domains like *.domain1.com and *.domain2.com under one certificate.
The type of certificate needed depends on the intended implementation, security requirements, validation protocols and desired interface cues like green address bars. Carefully matching certificate type to needs ensures cost-effective usage.
Choose Your Wildcard SSL Certificate from the Trusted Certificate Authorities
| Product Features | RapidSSL Wildcard Certificate | Wildcard SSL Certificate | Sectigo PositiveSSL Wildcard | GeoTrust QuickSSL Premium Wildcard |
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| Certificate Authority |  RapidSSL  |
 SSL.com |
 Sectigo |
 GeoTrust |
| Unlimited Subdomains | Unlimited Subdomains | Unlimited Subdomains | Unlimited Subdomains | |
| Main Domain + All Sub-domains | Main Domain + All Sub-domains | Main Domain + All Sub-domains | Main Domain + All Sub-domains | |
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| Domain | Organization | Domain | Domain | |
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| Minutes | 5 Minutes | Minutes | Instant | |
| up to 256-bit | up to 256-bit | up to 256-bit | up to 256-bit | |
| 2048 bits | 2048 bits | 2048 bits | 2048 bits | |
| Medium | High | Medium | Medium | |
| Unlimited | Unlimited | Unlimited | Unlimited | |
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| $10,000 | $1,250,000 | $50,000 | $500,000 | |
| 30 days | 30-Day | 30 days | 30 days | |
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| 99% | 99% | 99% | 99% | |
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| 24/7 Live Chat | 24/7 Live Chat | 24/7 Live Chat | 24/7 Live Chat |
Wildcard SSL Deployment
Once purchased, deploying a Wildcard SSL certificate involves the following main steps:
- Download the certificate file package from your certificate authority.
- Use a tool like OpenSSL to convert the certificate file formats to ones supported by your web server.
- On your web server, install the Wildcard certificate along with intermediate and root certificates.
- Configure the web server to use the certificate for HTTPS on port 443 by default at the domain level.
- Set up redirect rules to force all HTTP traffic on any subdomain to HTTPS using 301 redirects.
- Implement HTTP Strict Transport Security (HSTS) for added security on modern browsers.
- Check availability of secured connections using the SSL test tool on sites like SSL Labs.
- Configure automatic renewal of the certificate before expiration through server auto-renewal features.
Proper deployment is key to ensuring all subdomains are seamlessly secured as intended and remain so via renewal automation. Consult server documentation for specific configuration details.
Advantages Over Individual Subdomain Certificates
Compared to securing each subdomain with a separate SSL certificate, Wildcard SSL offers some clear advantages:
Simplified Ongoing Management
- Single point of certificate deployment, configuration and renewal
- No need to repeat process for every new subdomain
Centralized Security
- Ability to apply security patches and updates to one certificate deployed in one location
- Reduces risks compared to individual certs which may have inconsistent security configurations or expired certificates
Performance Boost
- Less SSL handshaking overhead compared to validating a certificate for each subdomain request
- Pages load faster since browser doesn’t need to establish secure connection repeatedly
Continued Trust in Subdomains
- Users see securely locked icon on all relevant subdomains from one trusted certificate
- Avoids mixed content warnings and broken padlock issues from some subdomains lacking SSL
Cost Savings Over Time
- While more expensive upfront, total lifetime cost is lower than aggregating individual certificate prices
- Savings grow larger as more subdomains are added and managed long-term
Easy Compliance with Security Standards
- Simplifies adhering to requirements like HSTS, SSL/TLS configuration standards across all applicable domains
- Avoids piecemeal compliance challenges of applying changes to many certificates
SEO and UX Benefits
- Provides more complete HTTPS implementation for better SEO ranking from search engines
- Users enjoy consistently secure, high-performance experiences across whole domain tree
FAQs on Wildcard SSL Certificate
How many subdomains can a single wildcard cover?
A valid wildcard SSL certificate can secure an unlimited number of first-level subdomains under the same base domain. There is no fixed limit to the number of subdomains a single certificate issuance will encrypt.
Do I need to renew the certificate for new subdomains?
No, any subdomains added after the wildcard certificate is issued will automatically be covered without needing to renew or reissue the certificate. As long as the base domain ownership can be validated, new subdomain additions are allowed under the scope of the wildcard.
Will it work on my server platform/technology?
Wildcard certificates are compatible with all major web and application servers, as well as desktop and mobile operating systems that support SSL/TLS encryption. As long as the SSL functions are enabled on your server software (e.g. Apache, Nginx) and the certificate issuer is trusted, it should work without issues.
Can a wildcard be installed on multiple servers?
Absolutely. A single wildcard SSL certificate containing the private key file can be deployed across as many web servers as needed to handle requests for the secured subdomains. Load balancers and failover servers are common use cases for multi-server wildcard installation.
What types of subdomains are supported?
Common valid uses of secured subdomains via a wildcard include branding (www), servers (mail, ftp), environments (staging, testing), mobile/apps, or internal tools. Almost any subdomain purpose is allowed as long as it resides directly under the base domain scope covered by the wildcard certificate.
How do I get a wildcard certificate?
Purchasing and obtaining a wildcard certificate is straightforward. Select a trusted certificate authority, choose wildcard SSL during the order process, validate domain ownership, complete payment, and the CA will issue the certificate files. Automated one-click installation is also usually available from the provider or directly within control panel software.