How to Publish New Certificate Revocation List (CRL) from Offline Root CA to Active Directory and Inetpub
It's highly recommended when building your Microsoft PKI (Public Key Infrastructure) to have your Root CA offline after issuing the Enterprise Sub CA certificates. It's recommended to minimize the access to the Offline Root CA as much as possible. The Root CA is not a domain joined machine and can be turned off without any problem. One of the Key issue is the CRL generated from the Root CA, you need to set the CRL interval for a large value so that we don’t need to copy the CRL to an online location frequently and do not implement delta CRLs, because the publication of each delta CRL would require access to the offline root CA in order to copy the delta CRL to an online publication location. In order to change the CRL interval you need to:
Turn on the Offline Root CA and login with Admin account
Open the Certification Authority Console
Right Click on the "Revoked Certificates" and click Properties.
Set “CRL Publish interval” to a large value (Default is 26 Weeks) and uncheck “Publish Delta CRL” check-box.
In order to Publish a new CRL from the offline Root CA to the Enterprise Sub CA you need to do the following:
Publish a new CRL on the Root CA, this can be done by Right Click the "Revoked Certificates" - All Tasks - Publish
Copy the CRL file from the Root CA located under %systemroot%\system32\certsrv\certenroll to the Sub CA Server
Turn off the Root CA
Copy the above file to the InetPub folder (HTTP Path) in the Sub CA server which is by default located under the C:\inetpub\wwwroot\Certdata
Open an Admin Command Prompt and run the following command to publish it to the Active Directory (LDAP Path).certutil -f -dspublish " C:\Inetpub\wwwroot\certdata\RootCA.crl
This process of renewing the CRL and publishing a new one is manually done since the Root CA is offline and thats why its better to make the CRL publish interval more than the default value so you won't do it frequently. You may also want to set an automated reminder before the next renewal date.