This question pertains to the configuration of basic storage services in Huawei OceanStor Dorado series storage systems. According to the *HCIP-Storage V5.5 Training Material (Module 4: Storage Design and Implementation)*, basic service configuration involves essential steps to enable storage access for hosts. The material outlines the following:

- Configuring connectivity between a host and the storage system (Option A) is mandatory, as it involves setting up physical or logical connections (e.g., Fibre Channel or iSCSI) to allow the host to communicate with the storage system. Without this, no storage services can be accessed.

- Creating a mapping (Option C) is also mandatory, as it maps LUNs to hosts or host groups, enabling the host to access specific storage resources. The material states: “Mapping is a critical step to associate LUNs with hosts for service access.”

- Creating a port group (Option B) is optional. Port groups are used to organize front-end ports for specific purposes (e.g., load balancing or zoning), but they are not always required, especially in simpler configurations where default port settings suffice.

- Creating a LUN group (Option D) is optional. LUN groups simplify management by grouping multiple LUNs for mapping, but they are not mandatory if LUNs are mapped individually.

Thus, options B and D are optional operations, as they are not always required for basic service configuration.