Network Information Service

Network Information Service

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Network Information Service (NIS), formerly known as Yellow Pages (YP), is a distributed directory service used in Unix and Unix-like operating systems to manage and centralize various system configuration data within a network. NIS allows administrators to store and retrieve critical network information, such as user accounts, passwords, group information, and other system configurations, from a central server, making it easier to manage and maintain consistent network-wide settings.

Key Components of NIS:

  1. NIS Server: The NIS server is a central machine that holds the master copy of the network’s configuration database. It is responsible for distributing the network information to NIS clients upon request.
  2. NIS Clients: NIS clients are the machines that request and use the network information stored on the NIS server. These clients access the centralized data and cache it locally for faster retrieval and improved performance.
  3. Maps (Databases): In NIS, the network information is organized into maps or databases. Each map represents a specific set of data, such as user accounts, passwords, group information, etc. The maps are stored on the NIS server and are distributed to NIS clients as needed.
  4. NIS Domain: An NIS domain is a logical grouping of systems that share the same NIS configuration data. All systems within an NIS domain can access the same centralized database.

NIS Operation:

  1. Database Management: The NIS server maintains the master copies of the maps (databases). When changes occur to the network information, such as adding new users or updating passwords, the server updates the corresponding maps.
  2. Map Distribution: Periodically, or upon changes, the NIS server distributes the updated maps to all NIS clients in the domain. The clients retrieve the maps and store them locally in their cache.
  3. Client Queries: When an NIS client needs specific network information, it queries its local NIS cache first. If the information is not available in the cache or is outdated, the client sends a request to the NIS server to fetch the required data.
  4. Map Merging: Upon receiving the data request, the NIS server sends the requested map to the client, which merges the new information with its local cache.

Advantages of NIS:

  • Centralized Management: NIS allows for centralized management of network information, reducing the administrative overhead of managing individual systems.
  • Consistency: NIS ensures that all systems within the domain have access to the same set of configuration data, promoting consistency across the network.
  • Scalability: NIS is scalable and can support large networks with numerous clients efficiently.

Security Considerations:

It is essential to secure NIS communication and database access since the data, including passwords, is transmitted over the network. Using secure communication protocols and proper access controls helps protect sensitive information from unauthorized access.


Network Information Service (NIS) provides a reliable and efficient way to centralize and manage network configuration data in Unix and Unix-like environments. By consolidating critical information on an NIS server and distributing it to NIS clients, system administrators can simplify network management tasks and ensure consistent configurations across the network. However, proper security measures should be implemented to protect the confidentiality and integrity of the transmitted data.

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