Chapter 8. Troubleshooting
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# Chapter 8. Troubleshooting

## Common Problems

### It's Not Working; How Can I Figure Out What's Wrong?

The best solution to installation and configuration issues is to take preventive measures by setting up logging files beforehand. The log files provide a source of hints and information that can be used to identify what went wrong and fix the problem.

## Incrementing and Changing the Serial Number

Zone serial numbers are just numbers — they are not date-related. However, many people set them to a number that represents a date, usually of the form YYYYMMDDRR. Occasionally they make a mistake and set the serial number to a date in the future, then try to correct it by setting it to the current date. This causes problems because serial numbers are used to indicate that a zone has been updated. If the serial number on the secondary server is lower than the serial number on the primary, the secondary server attempts to update its copy of the zone.

Setting the serial number to a lower number on the primary server than the one on the secondary server means that the secondary will not perform updates to its copy of the zone.

The solution to this is to add 2147483647 (2^31-1) to the number, reload the zone and make sure all secondaries have updated to the new zone serial number, then reset it to the desired number and reload the zone again.

## Where Can I Get Help?

The BIND-users mailing list, at https://lists.isc.org/mailman/listinfo/bind-users, is an excellent resource for peer user support. In addition, ISC maintains a Knowledgebase of helpful articles at https://kb.isc.org.

Internet Systems Consortium (ISC) offers annual support agreements for BIND9, ISC DHCP, and Kea DHCP. All paid support contracts include advance security notifications; some levels include service level agreements (SLAs), premium software features, and increased priority on bug fixes and feature requests.

Please contact info@isc.org or visit https://www.isc.org/contact/ for more information.

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Chapter 7. BIND 9 Security Considerations | Home | Appendix A. Release Notes

BIND 9.11.35 (Extended Support Version)