Analysis and Geoprocessing
Geoprocessing questions test your grasp of tool mechanics, parameters, and spatial logic. Every tool has inputs, parameters, and outputs; many tools write a new dataset, while others (like Calculate Field or Add Field) modify in place. Know the environment settings that silently shape results: output coordinate system, processing extent, snap raster, cell size, and mask. A common trap is a result clipped or shifted because the processing extent environment was set to a small layer.
Understand core tool families. Overlay tools (Clip, Intersect, Union, Erase, Spatial Join) combine geometry; remember that Clip cuts but keeps attributes of the input, while Intersect keeps attributes from both. Proximity tools (Buffer, Near, Generate Near Table) measure distance; buffers use the input's coordinate system units unless you specify otherwise, so a geographic coordinate system produces unreliable distances. Selection tools (Select by Attribute, Select by Location) create selections you can then export or use as tool inputs.
ModelBuilder chains tools into a model with variables and parameters, enabling repeatable workflows. Geoprocessing history records what ran and with which parameters, useful for reproducing results.
Worked example
You buffer points by 500 meters. If the layer is in a geographic coordinate system, the buffer distance is interpreted in degrees and results are wrong. Rule of thumb: project to a suitable projected coordinate system before any distance or area analysis, or set an appropriate output coordinate system environment.
Other traps: assuming tools overwrite outputs (they fail if the output exists unless overwrite is enabled), and confusing Spatial Join (combines attributes by location) with Join Field (table-only).