Wildcard Certificate

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What Does Wildcard Certificate Mean?

A wildcard certificate is a digital public key document that can be applied to a domain and subdomains. It has the advantage of simultaneously covering an unlimited number of first-level subdomains and is, thus, more cost-effective and convenient with the increase of subdomains.


A wildcard certificate is also known as a wildcard Secure Sockets Layer (SSL) certificate.

Techopedia Explains Wildcard Certificate

A wildcard certificate may be applied to multiple first-level subdomains of a website or single domain. It secures the common domain name and all subdomains at the level specified during the request to the certification authority (CA), but it usually is applied to first-level subdomains. This means that a SSL certificate with a common name, like *.sampledomain.com, can be used without errors when it is used for any domain names that replaces the * character.

However, wildcard certificates only work for single-level, versus multiple-level, subdomains. Unified Communications Certificates (UCC SSL) are used to secure multiple levels of subdomains or totally different domains.

In the given example, a wildcard certificate works for:

  • market.sampledomain.com

  • blog.sampledomain.com

  • gallery.sampledomain.com

However, a wildcard certificate does not work for:

  • www.market.sampledomain.com

  • www1.here.sampledomain.com

  • this.is.a.long.domain.sampledomain.com


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Margaret Rouse
Technology Expert
Margaret Rouse
Technology Expert

Margaret is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical business audience. Over the past twenty years, her IT definitions have been published by Que in an encyclopedia of technology terms and cited in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine, and Discovery Magazine. She joined Techopedia in 2011. Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages.