SSL Certificate Monitoring: Never Let Your Certificate Expire

The Cost of an Expired SSL Certificate

When your SSL certificate expires, browsers show a full-page security warning that prevents users from accessing your site. This is not a minor inconvenience - it is a complete outage. Major companies including LinkedIn, Microsoft Teams, and Spotify have all suffered outages due to expired certificates.

How SSL Monitoring Works

SSL monitoring checks the expiration date of your TLS certificate at regular intervals and alerts you well before it expires. Sentrix checks SSL status with every uptime check, tracking how many days remain until expiration.

What Gets Checked

• Certificate validity and expiration date
• Certificate chain completeness
• Whether HTTP redirects to HTTPS properly
• HSTS header configuration

Best Practices

Use Auto-Renewal

Most certificate authorities and hosting providers support automatic renewal. If you use Let's Encrypt with certbot, set up a cron job for renewal. But even with auto-renewal, monitoring is essential because renewal can fail silently.

Monitor Multiple Domains

If you run multiple domains or subdomains, each has its own certificate. Make sure all of them are monitored. A wildcard certificate covers subdomains but still has a single expiration date.

Set Alert Thresholds

Get alerted 30 days, 14 days, and 7 days before expiration. This gives you plenty of time to renew even if the first alert is missed.

Monitoring with Sentrix

When you add an HTTPS monitor in Sentrix, SSL monitoring is included automatically. The dashboard shows the number of days until certificate expiration, and alerts are sent when the certificate is approaching its expiration date.