As of Firefox 24, the user-interface for importing CRLs via Firefox has been removed. Auto-importing/updating of CRLs through Firefox has also been removed. NSS still supports CRLs, but Firefox is moving away from checking CRLs, and moving towards using a revocation list push mechanism.

Do browsers check CRL?

There are two main technologies for browsers to check the revocation status of a particular certificate: the Online Certificate Status Protocol (OCSP) and Certificate Revocation Lists (CRLs). ... Firefox blocks access to certificates which have been revoked via OCSP.

How do I know if my CRL is accessible?

One of which is through using Google Chrome and checking the certificate details. To do this, open the Chrome DevTools, navigate to the security tab and click on View certificate. From here, click on Details, and scroll down to where you'll see "CRL Distribution Points".