It's no surprise that this one pops up often in DB2 basic interview questions. The four types of Db2 registry variables are: Db2 global-level profile registry: All server-wide environment variable settings reside in this registry. These settings are applicable to all the instances that pertain to a particular version of DB2. Db2 instance-level profile registry: The environment variable settings for a particular instance are stored in this registry. The values defined in this profile registry override any corresponding settings in the global-level profile registry. Db2 instance node-level profile registry: The environment variable settings that are specific to a node in a Massively Parallel Processing (MPP) database environment are stored in this registry. The values defined in this profile registry override any corresponding settings in the global-level and instance-level profile registries. DB2 user-level profile registry: The environment variable settings that are specific to each user are stored in this registry, and they take higher precedence over other profile registry settings.