[Home](./index.md) > [@snowplow/react-native-tracker](./react-native-tracker.md) > [SubjectConfiguration](./react-native-tracker.subjectconfiguration.md) ## SubjectConfiguration interface Configuration of subject properties tracked with events Signature: ```typescript export interface SubjectConfiguration ``` ## Properties | Property | Type | Description | | --- | --- | --- | | [colorDepth?](./react-native-tracker.subjectconfiguration.colordepth.md) | number | (Optional) Color depth (integer) | | [domainUserId?](./react-native-tracker.subjectconfiguration.domainuserid.md) | string | (Optional) The domain user id (DUID) is a generated identifier that is stored in a first party cookie on Web. The React Native tracker does not assign it automatically. | | [ipAddress?](./react-native-tracker.subjectconfiguration.ipaddress.md) | string | (Optional) Override the IP address of the device | | [language?](./react-native-tracker.subjectconfiguration.language.md) | string | (Optional) The language set in the device | | [networkUserId?](./react-native-tracker.subjectconfiguration.networkuserid.md) | string | (Optional) Override the network user id (UUIDv4) that is assigned by the collector and stored in cookies | | [screenResolution?](./react-native-tracker.subjectconfiguration.screenresolution.md) | [ScreenSize](./react-native-tracker.screensize.md) | (Optional) The screen resolution | | [screenViewport?](./react-native-tracker.subjectconfiguration.screenviewport.md) | [ScreenSize](./react-native-tracker.screensize.md) | (Optional) The screen viewport size | | [timezone?](./react-native-tracker.subjectconfiguration.timezone.md) | string | (Optional) The timezone label | | [useragent?](./react-native-tracker.subjectconfiguration.useragent.md) | string | (Optional) The custom user-agent. It overrides the user-agent used by default. | | [userId?](./react-native-tracker.subjectconfiguration.userid.md) | string | (Optional) Business-defined user ID for this user |