Guides

How SSL certificates, domains and email authentication work, what is changing, and how to fix the problems our free tools find. Each guide links to the tool that checks it.

• 7 MIN READ · UPDATED NOV 2026

  47-Day SSL Certificates: The 2026–2029 Validity Timeline

  SSL/TLS certificate validity drops from 398 to 200 days in March 2026, 100 days in 2027 and 47 days in 2029. What changes at each step and how to get ready.

• 8 MIN READ · UPDATED NOV 2026

  What Is DKIM? How DKIM Records Work and How to Set One Up

  DKIM explained: how email signing works, what a DKIM record and selector are, how to set up DKIM in Google Workspace and Microsoft 365, and why DKIM fails.

• 7 MIN READ · UPDATED NOV 2026

  Domain Expired? What Happens Next: Grace & Redemption

  What happens when a domain name expires: the grace period, redemption period and deletion, what stops working on day one, and how to check expiry dates.

• 6 MIN READ · UPDATED NOV 2026

  Your Connection Is Not Private: How Site Owners Fix It

  Why browsers show "Your connection is not private", what each error code means (ERR_CERT_DATE_INVALID and others), and how to fix the certificate on your site.

• 7 MIN READ · UPDATED NOV 2026

  How to Renew an SSL Certificate (and Catch Failed Renewals)

  How to renew an SSL certificate step by step, automatic renewal with ACME and certbot, why renewals fail without warning, and how to check the new one is live.