BIND: Max open files (1024) is smaller than max sockets (4096) Error and Solution

When running the BIND (Berkeley Internet Name Domain) DNS server on a Linux or Unix-based system, you may encounter the following error message:

This error message indicates that the maximum number of open files allowed by the system is less than the maximum number of sockets allowed by BIND. By default, the maximum number of open files in most Linux and Unix-based systems is set to 1024, which is not sufficient for BIND to function properly.

To fix this error, you need to increase the maximum number of open files allowed by the system to a value greater than the maximum number of sockets allowed by BIND. You can do this by following these steps:

1. Open the /etc/security/limits.conf file in a text editor.
2. Add the following lines to the end of the file:
   named soft nofile 4096
named hard nofile 4096


   These lines set the maximum number of open files for the named user (which is the user that BIND runs under) to 4096.

   Note: If you are using a different username or if you have multiple instances of BIND running under different usernames, you should replace named with the appropriate username(s).

3. Save the file and close the text editor.
4. Restart the BIND service to apply the changes.

   On most Linux and Unix-based systems, you can restart the BIND service by running the following command as root:

   systemctl restart named


   If you are using a different init system or if you have a custom BIND installation, you may need to use a different command to restart the service.

After following these steps, the max open files error should be resolved, and BIND should be able to function properly.