Final answer:
To mark an attribute as confidential and RODC Filtered, you need to modify the searchFlags attribute of the respective schema object using an LDAP tool.
Step-by-step explanation:
To mark an attribute as confidential and RODC Filtered in Active Directory, you need to change the searchFlags attribute of the respective schema object. The searchFlags is a bit-mask attribute, where each bit represents a different attribute property. To mark an attribute as confidential, you set the 7th bit to 1 (128 in decimal), and to make it RODC Filtered, you set the 10th bit to 1 (512 in decimal). You usually use a Lightweight Directory Access Protocol (LDAP) tool like LDP or ADSI Edit to make this change.
Learn more about searchFlags