Internet Explorer and CRLs

The CRLs contain the list of revoked, therefore non-valid, certificates.

IE 7 automatically consult the CRLs in order to check if the certificate displayed by a server during a SSL/TLS connection is still valid.

With Internet Explorer 6, you will have to activate the advanced option "check for certificates revocation".

For security matters, it is advised to activate this option even if it, sometimes, slows secured browsing.