Map image layers (map services) do not automatically detect schema changes, especially in registered enterprise geodatabases. Even with schema locking disabled, services cache the original schema at the time of publishing. To reflect the new field, you must overwrite the existing service.
From ArcGIS Server documentation:
"If the schema of a dataset is changed after a service is published (such as adding a field), the change is not automatically reflected in the service. You must overwrite the service or republish the map to reflect schema updates."
* Option B is not applicable; field visibility in the portal reflects what's in the published service definition.
* Option C is related to editing access, not field visibility.
* Option D is not a valid administrative action in this context.
Reference:ArcGIS Server - Schema Changes and Map Service Behavior

Topublish and serve cached image services, the ArcGIS Server must be licensed as anImage Server. This licensing role is designed specifically for servingraster datasets,image services, andcache-based imagery workflows.
From ArcGIS Server documentation:
"The Image Server role is required to publish and manage image services, including those that serve pre- generated tile caches and support raster analytics."
* OptionA(GIS Server) supports feature and map services, butnot cached imagery.
* OptionC(Mission Server) is for real-time operations, unrelated to imagery or features.
Reference:ArcGIS Enterprise -Server Roles and Functionality (Image Server)

The Spatiotemporal big data store is designed for massive datasets and optimized for high-speed visualization, time-enabled querying, and big data analytics. It is ideal for storing millions of point features such as sensors or oil rig locations, especially when performance and scalability are critical.
From ArcGIS documentation:
"The spatiotemporal big data store is designed for writing and querying large volumes of spatial and temporal data. It's optimized for visualizing high-density datasets in web maps."
* Option B (Relational) works for moderate data volumes but may not scale well.
* Option C supports cached tiles, not dynamic feature access.
Reference:ArcGIS Enterprise - Choosing the Right Data Store Type for Large Datasets

When users perform standard analysis tasks in the portal Map Viewer, the hosting server executes geoprocessing operations that are computationally intensive. These operations require significant CPU resources. Monitoring CPU utilization helps ensure that the server can handle the increased load without performance degradation.
While disk activity and network utilization are important, they are less directly impacted by standard analysis tasks compared to CPU usage. Therefore, CPU utilization is the primary resource to monitor in this scenario.
Reference Source: ArcGIS Enterprise documentation on system performance monitoring.

Thewebgisdrutility is the official tool used to both back up and restore ArcGIS Enterprise deployments.
When restoring a backup, this tool ensures all components-Portal for ArcGIS, ArcGIS Server (federated), ArcGIS Data Store, and associated configurations-are restored in the correct sequence and with integrity.
The utility reads from a configuration file that defines the backup location, type, and parameters.webgisdr orchestrates the entire restoration process automatically. Runningrestoredatastore(Option B) individually is not required and may only restore part of the deployment, such as the relational store.Restore(Option C) is not a valid utility for ArcGIS Enterprise.
Reference Source:ArcGIS Enterprise documentation - Web GIS Disaster Recovery tool (webgisdr)