This glossary covers the core terminology you’ll need to understand when working with the Nautobot Data Modeling Layer:

• Model: A digital representation of a network resource within Nautobot, such as a device, interface, or site. Models form the foundation of data organization.
• ForeignKey: A field used to define a relationship from one model to another, enabling associations like one-to-many and many-to-one between network objects.
• Relationship: A user-defined link between Nautobot objects, allowing custom associations beyond the built-in model structure to support complex use cases.
• Versioned Model: A model with built-in tracking for changes over time, useful for representing dynamic network states (e.g., Devices, IP Addresses).
• Non-Versioned Model: A model used mainly in application logic, typically not version-controlled, such as Users and Permissions.

Nautobot models are interconnected using several types of relationships. These relationships define how data objects link and contextualize one another across your network infrastructure.

• One-to-One: Each instance of a model is linked to a single instance of another model. Implemented using OneToOneField.
  Example: A Device linked to its primary VirtualChassis.
• One-to-Many: One model instance relates to many instances of another. Implemented using ForeignKey or a custom Relationship.
  Example: A Site related to multiple Devices.
• Many-to-One: Many instances of one model relate to a single instance of another. This is typically the reverse direction of One-to-Many.
  Example: Many Interfaces associated with a single Device.
• Many-to-Many: Multiple instances of one model relate to multiple instances of another. Implemented using ManyToManyField or custom relationships.
  Example: A VRF associated with multiple RouteTargets, and vice versa.

For more flexible use cases, Nautobot's custom Relationships feature allows you to define reversible and dynamic associations between any two models — whether built-in or part of an App.

Nautobot’s data model is organized into several core domains that structure how network information is captured, managed, and analyzed. Understanding these domains helps you navigate and extend Nautobot for your use case:

• Inventory: Encompasses all physical resources in the network, including devices, racks, and sites. This domain provides a complete picture of the hardware assets and their organization within your infrastructure.
• Circuits: Represents communications circuits and service providers. This domain models WAN links, service agreements, and the logical connection points between different geographic or organizational locations.
• IP Addresses: Deals with the planning, allocation, and management of IP addresses, prefixes, VLANs, and VRFs. This domain supports efficient routing, address assignment, and network segmentation.

Each domain is tightly integrated with the others, enabling Nautobot to deliver a comprehensive and accurate view of the network as a flexible source of truth for automation and operations.

Nautobot provides powerful features to extend its core data model, allowing you to tailor the platform to your organization’s specific operational and business requirements. The key mechanisms for custom model extension include:

• Relationships Feature: Enables you to create custom, user-defined relationships between Nautobot objects beyond the native model structure. For example, linking an IP Address directly to a Circuit can model circuit endpoints more precisely. These relationships are reversible and configurable through the Nautobot web interface under Extensibility → Relationships.
• Custom Fields: Add additional attributes to existing models without modifying the underlying source code. This lets you capture extra data points specific to your network environment.
• Nautobot Apps: Extend the platform by developing application-specific data models that subclass Nautobot Core Models. Apps can leverage the native features of Nautobot such as relationships, custom fields, statuses, export templates, and API exposure via GraphQL, enabling deep integration with the core platform.
• Signal-Driven Automation: Use custom signals like nautobot_database_ready to programmatically create or update extensibility features such as relationships or custom fields when your app is installed or upgraded, ensuring consistent data model enhancements.

These extensibility options allow you to maintain a flexible yet consistent network source of truth, adapting Nautobot’s data model precisely to your evolving needs.

Data model versioning is a powerful capability in Nautobot that allows you to track, audit, and revert changes to your network’s source of truth over time. When enabled for specific models, Nautobot captures historical snapshots of records so you always know what changed, when, and by whom.

This is especially useful for dynamic models that represent operational network state, such as devices, IP address assignments, and interfaces.

• Change Tracking: Every modification to versioned data (create, update, or delete) is recorded, providing complete traceability.
• Rollback Capability: Enables recovery to previous states in case of misconfiguration or user error.
• Auditing & Governance: Supports compliance and security requirements by exposing a clear and immutable history of changes.
• Collaboration Support: Teams can work confidently with shared models, knowing changes are tracked and recoverable.

Versioning is typically applied to models representing network state — such as Device, Interface, IPAddress, and similar — giving you fine-grained visibility into the evolution of your infrastructure.