rndc

rndc (Remote Name Daemon Control) is a command-line tool used to manage and control the operation of the BIND (Berkeley Internet Name Domain) DNS (Domain Name System) server. It provides a way to interact with the BIND server, enabling administrators to perform various administrative tasks remotely.

Overview of rndc

Purpose

The primary purpose of rndc is to manage the operation of the BIND server, including starting and stopping the server, reloading configuration files, checking server status, and updating DNS zones dynamically.

Basic Usage

The general syntax for rndc commands is:

rndc [options] <command> [command-options]

Common rndc Commands and Subcommands

1. reload

   • Purpose: Reloads the configuration file for BIND without interrupting the service.

   • Usage:

     rndc reload

   • Effect: Applies changes made to the BIND configuration file (named.conf) without restarting the server.

2. restart

   • Purpose: Restarts the BIND server, applying any changes made to the configuration file.

   • Usage:

     rndc restart

   • Effect: Completely stops and starts the BIND server, applying all configuration changes.

3. status

   • Purpose: Checks the current status of the BIND server.

   • Usage:

     rndc status

   • Effect: Provides information about the server's current operation, including uptime, version, and current configuration.

4. stop

   • Purpose: Stops the BIND server.

   • Usage:

     rndc stop

   • Effect: Gracefully stops the BIND server, terminating its operation.

5. start

   • Purpose: Starts the BIND server if it is not running.

   • Usage:

     rndc start

   • Effect: Initiates the BIND server if it is not already running.

6. reconfig

   • Purpose: Reconfigures the BIND server by re-reading its configuration file (named.conf).

   • Usage:

     rndc reconfig

   • Effect: Re-applies the server configuration without stopping and starting the service.

7. flush

   • Purpose: Flushes the server's cache, removing all cached DNS data.

   • Usage:

     rndc flush [view]

   • Effect: Clears the DNS cache of the specified view (if multiple views are configured).

8. freeze and thaw

   • freeze Purpose: Suspends updates to a dynamic zone.

     rndc freeze <zone>

   • thaw Purpose: Resumes updates to a frozen dynamic zone.

     rndc thaw <zone>

9. addzone and delzone

   • addzone Purpose: Dynamically adds a zone to the server's configuration.

     rndc addzone <zone> <options>

   • delzone Purpose: Dynamically removes a zone from the server's configuration.

     rndc delzone <zone>

Integration with BIND

• rndc communicates with the BIND server through a control channel (rndc.conf), typically configured in the BIND configuration file (named.conf).

• It requires appropriate permissions and authentication (often controlled by keys) to execute commands securely.

Security Considerations

• Secure rndc communications using keys and encryption to prevent unauthorized access.

• Restrict access to rndc commands and control channel to trusted administrators.

Conclusion

rndc is a powerful tool for managing and controlling the BIND DNS server, allowing administrators to perform various administrative tasks remotely. Understanding its commands and options is essential for efficiently managing DNS infrastructure and ensuring smooth operation.