DNS (Domain Name System) is a critical component of the internet infrastructure, translating human-readable domain names into IP addresses. Proper DNS configuration is essential for website accessibility. This knowledge base aims to address common DNS configuration errors and provide step-by-step solutions.

Table of Contents

1. Incorrect DNS Records

   • 1.1. A Record Misconfiguration

   • 1.2. CNAME Record Issues

2. Propagation Delays

   • 2.1. Understanding DNS Propagation

   • 2.2. Checking Propagation Status

3. MX Record Problems

   • 3.1. Incorrect Mail Server Configuration

   • 3.2. Priority Misconfiguration

4. Nameserver Configuration

   • 4.1. Nameserver Not Set or Misconfigured

   • 4.2. Glue Records Missing

5. DNSSEC Configuration Errors

   • 5.1. Invalid DNSSEC Records

   • 5.2. Misconfigured DS Records

6. Reverse DNS Issues

   • 6.1. Missing Reverse DNS Entry

   • 6.2. Misconfigured PTR Records

7. Firewall and Port Blocking

   • 7.1. Firewall Blocking DNS Requests

   • 7.2. Port 53 Access

8. Expired or Invalid SSL Certificate

   • 8.1. SSL/TLS Handshake Errors

   • 8.2. Certificate Chain Issues

9. Registrar and DNS Hosting Provider Errors

   • 9.1. Incorrect DNS Server Settings

   • 9.2. Registrar Locks

10. IPv6 Configuration Problems

    • 10.1. Missing IPv6 Records

    • 10.2. Incorrect IPv6 Address Formatting

1. Incorrect DNS Records

1.1. A Record Misconfiguration

Check the A records for your domain:

1. Log in to your DNS hosting provider's dashboard.

2. Verify that the A records point to the correct IP addresses.

1.2. CNAME Record Issues

If using CNAME records:

1. Ensure CNAME records are not pointing to an IP address.

2. Double-check the target domain for the CNAME.

2. Propagation Delays

2.1. Understanding DNS Propagation

Understand that DNS changes take time to propagate globally. It can take up to 48 hours.

2.2. Checking Propagation Status

Use online tools to check DNS propagation status. Wait for complete propagation before troubleshooting further.

3. MX Record Problems

3.1. Incorrect Mail Server Configuration

Check MX records for email:

1. Verify that MX records point to the correct mail server.

2. Confirm that mail server settings are accurate.

3.2. Priority Misconfiguration

Ensure correct priority for MX records:

1. Lower numbers have higher priority. Confirm they are in the correct order.

4. Nameserver Configuration

4.1. Nameserver Not Set or Misconfigured

Verify nameserver settings:

1. Ensure that nameservers are correctly set with your registrar.

2. Confirm that the nameservers are reachable and responding.

4.2. Glue Records Missing

If using custom nameservers:

1. Ensure that the glue records are correctly set at the domain registrar.

5. DNSSEC Configuration Errors

5.1. Invalid DNSSEC Records

If using DNSSEC:

1. Check for any invalid or expired DNSSEC records.

2. Use DNSSEC validation tools to identify and rectify issues.

5.2. Misconfigured DS Records

Ensure that DS (Delegation Signer) records are correctly configured at the parent domain's registrar.

6. Reverse DNS Issues

6.1. Missing Reverse DNS Entry

Contact your hosting provider or network administrator to set up a reverse DNS entry for your server's IP address.

6.2. Misconfigured PTR Records

Verify that PTR records are correctly configured in your DNS settings to match the reverse DNS entry.

7. Firewall and Port Blocking

7.1. Firewall Blocking DNS Requests

Check server or network firewall settings to ensure that DNS requests (UDP port 53) are allowed.

7.2. Port 53 Access

Verify that UDP port 53 is not blocked by your ISP or network provider.

8. Expired or Invalid SSL Certificate

8.1. SSL/TLS Handshake Errors

If SSL/TLS handshake errors occur:

1. Ensure that the SSL certificate is valid and not expired.

2. Check that the correct certificate files are installed on the server.

8.2. Certificate Chain Issues

Verify that the certificate chain is correctly configured, including any intermediate certificates.

9. Registrar and DNS Hosting Provider Errors

9.1. Incorrect DNS Server Settings

Ensure that the DNS servers provided by your registrar or DNS hosting provider are correct.

9.2. Registrar Locks

Check if there are any locks or restrictions on your domain at the registrar's end that might be affecting DNS changes.

10. IPv6 Configuration Problems

10.1. Missing IPv6 Records

If using IPv6, ensure that AAAA records are correctly configured.

10.2. Incorrect IPv6 Address Formatting

Verify that IPv6 addresses are correctly formatted in DNS records.

This knowledge base covers common DNS configuration errors and provides step-by-step solutions. If issues persist, consult with your DNS hosting provider, registrar, or network administrator for further assistance.