Creating new CI classes is ahigh-impact configuration activityand must follow strictData Foundations and CSDM-aligned best practicesto avoid long-term technical debt and upgrade risk.

Option Bis a recommended first step. Before creating any new CI class, administrators shouldinstall or update the CMDB CI Class Models Store applicationand verify whether an appropriate class already exists. ServiceNow frequently delivers new CI classes through updates and class model packages, and duplicating an existing or planned class can lead to fragmentation and governance issues.

Option Cis also correct. When a new class is truly required, it should beadded under an appropriate parent classto inherit attributes, behaviors, and discovery patterns. For an IoT Sensor, this might be under a hardware or device-related parent class, ensuring consistency and minimizing customization.

Option A is incorrect and dangerous—deleting unused classes can break dependencies and historical data. Option D is also discouraged; modifying existing classes to repurpose them violates upgrade-safe design principles and can negatively impact discovery, integrations, and reporting.

By verifying existing models first and extending the class hierarchy correctly, organizations maintain aclean, scalable, and upgrade-safe CMDB.

Therefore, the correct answers areB and C.