Introduction

DNS EDNS version not supported when server does not handle higher version. This guide provides step-by-step diagnosis and resolution.

Symptoms

Typical error output:

bash
Error: DNS operation failed
dig @server domain.com
Check DNS logs for details

Common Causes

  1. 1.DNSSEC chain of trust broken
  2. 2.Signature or key expired
  3. 3.Zone misconfiguration
  4. 4.Network or firewall issue

Step-by-Step Fix

Step 1: Check Current State

bash
dig @8.8.8.8 example.com +dnssec
dig @server example.com AXFR
named-checkzone example.com zonefile

Step 2: Identify Root Cause

bash
dig @localhost domain.com +dnssec
named-checkzone domain.com zonefile
named-checkconf

Step 3: Apply Primary Fix

bash
# Primary fix: Update zone configuration
named-checkzone example.com /etc/bind/db.example
rndc reload example.com
dig @localhost example.com +dnssec

Step 4: Apply Alternative Fix

bash
# Alternative fix: Check logs
tail -f /var/log/named/named.log
named-checkconf
rndc status

Step 5: Verify the Fix

bash
dig @localhost example.com +dnssec
dig @localhost example.com +trace
# Response should be NOERROR with DNSSEC records

Common Pitfalls

  • Not waiting for DNS propagation after changes
  • Forgetting to increment SOA serial
  • Using incorrect TTL values
  • Not testing DNSSEC before publishing

Best Practices

  • Use DNSSEC monitoring for chain validation
  • Implement proper key roll procedures
  • Test zone transfers regularly
  • Monitor DNS query rates and errors
  • DNS Resolution Failed
  • DNS Server Not Responding
  • DNS Cache Poisoning
  • DNS DDoS Attack