Wildcard SSL Guide: Protect All Your Subdomains with One Certificate
· Guide
A Wildcard SSL certificate secures a domain and all its first-level subdomains with a single certificate issued in the *.example.com format, where the asterisk matches any subdomain name.
What Does It Cover?
A *.example.com Wildcard covers www, mail, api, shop, blog — any single-level subdomain. However, second-level subdomains like dev.api.example.com fall outside the scope and require a separate certificate.
Wildcard vs Multi-Domain (SAN)
A Wildcard covers subdomains of one domain. A Multi-Domain (SAN) certificate groups entirely different domain names (example.com, example.net, mystore.io) under one certificate. Both reduce cost and management overhead; the right choice depends on your infrastructure.
Advantages
Cost savings (one payment for dozens of subdomains), simplified renewal (one cert to track), instant coverage for new subdomains, and optional OV/EV validation for corporate identity.
Security Consideration
If the Wildcard private key is compromised, all covered subdomains are at risk. Use HSM-based key management and rotate the certificate immediately upon any suspected breach.
Visit the PekiSSL product page to find the right certificate for your needs.