Knowledgebase

This guide addresses a common questions and issues in Virtualmin related to DNS configuration.

How do I setup nameservers for my server#

By carefully setting up and registering your custom nameservers, and configuring them correctly in Virtualmin, you can achieve a more personalized and professional setup for your hosting environment.

When setting up custom nameservers in Virtualmin, it’s important to properly configure both your domain registrar settings and your server settings. This ensures that your server can effectively handle DNS requests for your domain.

Configuring nameservers at your domain registrar#

• Start by registering your server as a nameserver with your domain registrar. For example, you might use names like ns1.example.com and ns2.example.com.
• Assign these nameservers to the IP addresses of your server. This step is crucial as it tells the global DNS system where to find the DNS information for domains hosted on your server.
• The registration process varies among registrars. Typically, it involves logging into your domain registrar’s control panel and entering your nameserver details. Check your registrar’s support documentation for specific instructions.

Setting up nameservers in Virtualmin#

After registering your nameservers:

1. Create DNS records for existing domain:

   • In Virtualmin, select your primary domain, e.g. example.com.
   • Navigate to DNS Settings ⇾ DNS Records page.
   • Add A - IPv4 Address records for ns1.example.com and ns2.example.com, pointing to your server’s IP addresses.

2. Configure DNS template for new domains:

   • Go to System Settings ⇾ Server Templates ⇾ Default Settings ⇾ DNS domain page.
   • In the Primary DNS server hostname, input the primary nameserver, e.g. ns1.example.com.
   • In the Additional manually configured nameservers field, list any additional nameservers, such as ns2.example.com.
   • This setup tells Virtualmin to include these nameservers in the DNS records for all new domains created on the server.

Important considerations#

• DNS propagation: After making changes to your DNS settings or nameserver configuration, allow some time for these changes to propagate across the internet. This process can take anywhere from a few hours to up to 48 hours.
• Consistency and accuracy: Ensure that the nameserver names and IP addresses are consistent and accurately entered both in your registrar’s settings and in Virtualmin. Errors in this setup can lead to DNS resolution issues for your domains.

Resolving DNS issues#

DNS issues are commonly encountered in virtual hosting systems due to the multiple systems that need to cooperate. Correct DNS settings are crucial for the smooth operation of various services on a hosting system.

Glue records#

Glue records are essential for DNS functionality and need to be correct at your domain registrar:

• Use the whois command to check glue records:

  whois example.com
  

• Look for the “name server” records. These should list your DNS servers.
• Remember, Virtualmin cannot modify your registrar’s records. Any necessary changes must be made using your registrar’s tools.

NS records#

NS (Name Server) records on your Virtualmin server should align with your glue records:

• Verify NS records using:

  host -t NS example.com
  

• Mismatches between NS records and glue records can cause intermittent DNS resolution issues.

A records#

A (Address) records map domain names to IP addresses:

• Check A records with:

  host example.com
  

• To specify a nameserver for the query:

  host example.com ns1.example.com
  

• Or use an IP if the nameserver’s IP address is uncertain:

  host example.com 192.168.1.1
  

MX records#

MX (Mail Exchanger) records direct how emails should be routed:

• Use the following command to inspect MX records:

  host -t MX example.com
  

Further resources#

• For more detailed troubleshooting, refer to the BIND Troubleshooting Tools in the Webmin documentation.

Remember, DNS issues often stem from misconfigurations across different systems, including your domain registrar and your Virtualmin server. Ensuring consistency and correctness in these configurations is key to resolving DNS-related problems.

Using cloud DNS providers#

When utilizing cloud-based DNS providers like Cloudflare, it’s important to understand how their proxy services interact with your server’s configuration. Specifically, services like Webmin and mail may become inaccessible if they’re running on ports not supported by Cloudflare’s proxy.

Cloudflare proxy and port limitations#

Cloudflare enhances security and performance by acting as a proxy between your server and the internet. However, it only proxies specific ports, which can affect access to services running on non-standard ports such as Webmin and mail services.

• Default port issue: By default, Webmin listens on port 10000, which is not among the ports that Cloudflare proxies. Similarly, mail services (SMTP, IMAP, POP3) use ports that are not supported by Cloudflare’s proxy.

• Supported ports: Cloudflare proxies the following ports:

  • HTTP ports: 80, 8080, 8880, 2052, 2082, 2086, 2095
  • HTTPS ports: 443, 2053, 2083, 2087, 2096, 8443

  To keep Webmin accessible through Cloudflare’s proxy, you need to configure Webmin to listen on one of these supported ports, such as 8443.

Changing Webmin ports for Cloudflare compatibility#

To ensure Webmin remains accessible while using Cloudflare’s proxy services, adjust the port Webmin listens on to one that is supported.

1. Access Webmin configuration:

   • Log in to your Webmin interface.
   • Navigate to Webmin ⇾ Webmin Configuration.

2. Modify listening port:

   • Click on Ports and Addresses.
   • In the Listen on port field, enter an allowed port, e.g., 8443.
   • Click Save to apply the new settings.

Mail services and Cloudflare#

Mail services (SMTP, IMAP, POP3) are not supported by Cloudflare’s proxy. If you enable the proxy (orange cloud icon) for your mail-related DNS records, email delivery will fail.

Ensure that the DNS records for your mail services have the proxy disabled (gray cloud icon). This applies to:

• MX records: Direct mail servers for your domain.
• Mail-related A records: Such as mail.example.com, which should have the proxy disabled.

By disabling the proxy for these records, mail traffic will bypass Cloudflare and connect directly to your server, ensuring proper mail delivery.

Important considerations#

• Firewall adjustments: Update your server’s firewall settings to allow incoming connections on the new port 8443 after changing Webmin’s port.

Additional resources#

• Supported ports: For a complete list of ports and additional details, refer to Cloudflare’s official documentation.

• Webmin configuration guidance: For more information on adjusting Webmin settings, see the Webmin Configuration documentation.