Quick answer
A practical guide to SSL certificate expiry monitoring, TLS checks, renewal failures, and alerting before browsers start rejecting customers.
Why SSL expiry deserves its own alert
HTTPS can keep working normally right up until a certificate expires. Then browsers can reject the connection, causing an incident that a generic uptime check may detect only after customers are already affected.
Monitor the live certificate
An effective SSL monitor reads the certificate presented by the live HTTPS connection and tracks its expiration time. This catches problems with renewal jobs, configuration changes, and certificates that were replaced with an unexpected value.
Do not confuse certificate monitoring with domain monitoring
A domain can remain registered while its certificate is expired, and a certificate can have plenty of life left while the domain is close to renewal. Treat the two as separate operational assets.
Alert before the deadline
The useful warning window depends on your renewal process. PingStag tracks the certificate expiry date and can send warnings before the certificate becomes an outage.
Sources and references
Related PingStag guides
Detecting Defacement: Why Keyword Matching is Crucial
Your server is returning a 200 OK, but hackers replaced your homepage. How exact string matching prevents disaster.
Don't Lose Your Brand: Automating Global Registry Tracking
Expired domains are immediately sniped by malicious bots. Why automated RDAP registry tracking is non-negotiable.
The 'Not Secure' Screen of Death: Automating SSL Tracking
Chrome's red warning screen instantly kills sales. How automated peer certificate extraction prevents SSL disasters.
Zero-Install Monitoring: Why Agentless Architecture Wins
Installing third-party daemons on your servers creates security risks. Learn why external pinging is safer.
