正解:D
Certificate authorities (CAs) are responsible for issuing, renewing, revoking, and publishing digital certificates. They also maintain a certificate revocation list (CRL), which is a database of revoked certificates that can be checked by relying parties to verify the validity of a certificate. Registration authorities (RAs) are entities that assist CAs with the verification of user identities and enrollment requests. They do not issue certificates themselves, nor do they have access to the CRL. Therefore, CRL publishing is a function that is performed by CAs but is a limitation of RAs. References := Some possible references are:
* Implementing and Operating Cisco Security Core Technologies (SCOR) v1.0, Module 4: Secure Connectivity, Lesson 4.1: VPN Fundamentals, Topic 4.1.1: Public Key Infrastructure (PKI)
* Easy guide to SSL certificate authorities, Namecheap
* How exactly are registration authorities related to certificate authorities?, Information Security Stack Exchange