InServiceNow, tables are structured in a hierarchical format wheresome tables can extend others, inheriting fields and properties. However, there are specific tables thatdo not extend any other table but can be extended—these are known asBase Tables.

Base Tables:

ABase Tableis a table thatdoes not extend another tablebutcan be extended by other tables.

It serves as afoundationfor creating new tables.

Example:

Task Table (task)– TheIncident, Problem, and Change tablesextend from the Task table.

Configuration Item Table (cmdb_ci)– Used as a base for various CI types.

Core Tables:

Core Tablesare thestandard tablesprovided by ServiceNow.

Theycan be base tables or extended tablesdepending on their role.

Example:

Task (task)andUser (sys_user)are core tables, but onlysome core tables are base tables.

Extended Tables:

Extended Tablesare tables thatinherit fields and functionalityfrom aparent table.

Example:

Incident (incident)extends fromTask (task).

Custom Tables:

Custom Tablesare tables thatdevelopers create for specific business needs.

They may or may not extend another table depending on their design.

Understanding Table Types in ServiceNow

Why Answer " A " is Correct:✔️ " Base Tables " are tables that may be extended by other tables but do not extend another table.

These tablesdo not inherit fieldsfrom any other table.

They provide thefoundation for extensions, making them the top-level tables in ServiceNow’s data hierarchy.

Example: TheTask tableis a base table because it does not extend another table but serves as the foundation for many other tables (e.g., Incident, Problem, Change).

Why the Other Answers Are Incorrect:B. " Core Tables "

IncorrectbecauseCore Tables are standard ServiceNow tables, but theycan be either base or extended tables.

Not all core tables follow the definition of a base table.

C. " Extended Tables "

Incorrectbecause extended tablesinherit fields from parent tables, meaning theydo extend another table.

Example: TheIncident table extends from the Task table, making it anextended table.

D. " Custom Tables "

IncorrectbecauseCustom Tablescan beeither base or extended tablesdepending on how they are created.

If a developer chooses to extend an existing table, then it isnot a base table.

ServiceNow CSA Study Guide – Data Schema & Tables

ServiceNow Docs: Table Hierarchy & Extensions(ServiceNow Documentation)

ServiceNow Data Model Overview (Base Tables & Extended Tables)

References from the Certified System Administrator (CSA) Documentation: