### 4.9.7 CRL issuance frequency
CRLs must be available via a publicly-accessible HTTP URL (i.e., "published").
Within twenty-four (24) hours of issuing its first Certificate, the CA MUST generate and publish either:
- a full and complete CRL; OR
- partitioned (i.e., "sharded") CRLs that, when aggregated, represent the equivalent of a full and complete CRL.
CAs issuing Subscriber Certificates:
1. MUST update and publish a new CRL at least every:
- seven (7) days if all Certificates include an Authority Information Access extension with an id-ad-ocsp accessMethod (“AIA OCSP pointer”); or
- four (4) days in all other cases;
2. MUST update and publish a new CRL within twenty-four (24) hours after recording a Certificate as revoked.
CAs issuing CA Certificates:
1. MUST update and publish a new CRL at least every twelve (12) months;
2. MUST update and publish a new CRL within twenty-four (24) hours after recording a Certificate as revoked.
CAs MUST continue issuing CRLs until one of the following is true:
- all Subordinate CA Certificates containing the same Subject Public Key are expired or revoked; OR
- the corresponding Subordinate CA Private Key is destroyed.