The SNMP provider returns a subset of the properties present for a class definition because the SNMP agent does not return properties that are defined as optional.

[This is preliminary documentation and subject to change.]

Further description:

The SNMP provider uses both GET-NEXT and GET operations to retrieve instance information from a device. The device may fail to generate responses for all properties of a given instance because the properties are defined as optional.

Solution:

This is the expected behavior.