Understanding DNS Settings

Oct 13, 2025 by wbrum.org 148 views

Introduction

Configuring DNS settings on Debian 12 is a crucial step in managing your Domain Name System (DNS) on your Virtual Private Server (VPS). The DNS is responsible for translating domain names into IP addresses that computers can understand. In this article, we will guide you through the process of configuring your DNS settings on Debian 12, specifically using a public resolver like 1.1.1.1 instead of your VPS host's resolver.

Understanding DNS Settings

Before we dive into the configuration process, it's essential to understand the basics of DNS settings. The DNS settings on your Debian 12 VPS are controlled by the /etc/resolv.conf file. This file contains the IP addresses of the DNS servers that your VPS will use to resolve domain names.

What is the `/etc/resolv.conf` file?

The /etc/resolv.conf file is a configuration file that contains the DNS resolver settings for your Debian 12 VPS. This file is used by the libc library to determine which DNS servers to use for resolving domain names.

What are the DNS resolver settings?

The DNS resolver settings in the /etc/resolv.conf file include the following:

nameserver: This specifies the IP address of the DNS server to use for resolving domain names.
search: This specifies the domain name to search for when resolving a domain name.
options: This specifies the options for the DNS resolver, such as whether to use TCP or UDP for DNS queries.

Configuring DNS Settings on Debian 12

To configure your DNS settings on Debian 12, you will need to edit the /etc/resolv.conf file. However, in Debian 12, the /etc/resolv.conf file is managed by the resolvconf service, which makes it more challenging to edit the file directly.

Using the `resolvconf` service

To configure your DNS settings using the resolvconf service, you will need to create a new file in the /etc/resolvconf/resolv.conf.d directory. This file will contain the DNS resolver settings that you want to use.

For example, to use the 1.1.1.1 public DNS resolver, you can create a new file called head in the /etc/resolvconf/resolv.conf.d directory with the following contents:

nameserver 1.1.1.1
nameserver 1.0.0.1

This will configure your Debian 12 VPS to use the 1.1.1.1 public DNS resolver.

Using the `systemd-resolved` service

Alternatively, you can use the systemd-resolved service to configure your DNS settings. The systemd-resolved service is a system service that manages the DNS resolver settings for your Debian 12 VPS.

To use the systemd-resolved service, you will need to create a new file in the /etc/systemd/resolved.conf directory. This file will contain the DNS resolver settings that you want to use.

For example, to use the 1.1.1.1 public DNS resolver, you can create a new file called resolved.conf in the /etc/systemd/resolved.conf directory with the following contents:

[Resolve]
DNS=1.1.1.1 1.0.0.1

This will configure your Debian 12 VPS to use the 1.1.1.1 public DNS resolver.

Verifying DNS Settings

Once you have configured your DNS settings, you will need to verify that they are working correctly. You can do this by using the dig command to query a domain name.

For example, to query the example.com domain name, you can use the following command:

dig example.com

This will display the DNS resolver settings that your Debian 12 VPS is using to resolve the example.com domain name.

Conclusion

Configuring DNS settings on Debian 12 is a crucial step in managing your Domain Name System (DNS) on your Virtual Private Server (VPS). In this article, we have guided you through the process of configuring your DNS settings on Debian 12, specifically using a public resolver like 1.1.1.1 instead of your VPS host's resolver. We have also discussed the importance of verifying your DNS settings to ensure that they are working correctly.

Additional Resources

Debian 12 documentation: https://www.debian.org/doc/manuals/debian-installer/
resolvconf service documentation: https://manpages.debian.org/bullseye/resolvconf.8
systemd-resolved service documentation: https://manpages.debian.org/bullseye/systemd-resolved.service

How to configure your DNS settings on Ubuntu 22.04: https://example.com/ubuntu-22.04-dns-config
How to configure your DNS settings on CentOS 8: https://example.com/centos-8-dns-config

Q: What is the purpose of the `/etc/resolv.conf` file in Debian 12?

A: The /etc/resolv.conf file is a configuration file that contains the DNS resolver settings for your Debian 12 VPS. This file is used by the libc library to determine which DNS servers to use for resolving domain names.

Q: Why can't I edit the `/etc/resolv.conf` file directly in Debian 12?

A: In Debian 12, the /etc/resolv.conf file is managed by the resolvconf service, which makes it more challenging to edit the file directly. Instead, you need to create a new file in the /etc/resolvconf/resolv.conf.d directory to configure your DNS settings.

Q: What is the difference between the `resolvconf` service and the `systemd-resolved` service?

A: The resolvconf service is a system service that manages the DNS resolver settings for your Debian 12 VPS. The systemd-resolved service is a system service that also manages the DNS resolver settings, but it is used by default in Debian 12. Both services can be used to configure your DNS settings, but the systemd-resolved service is more modern and flexible.

Q: How do I verify that my DNS settings are working correctly in Debian 12?

A: You can verify that your DNS settings are working correctly by using the dig command to query a domain name. For example, to query the example.com domain name, you can use the following command:

dig example.com

This will display the DNS resolver settings that your Debian 12 VPS is using to resolve the example.com domain name.

Q: Can I use a public DNS resolver like 1.1.1.1 with the `systemd-resolved` service?

A: Yes, you can use a public DNS resolver like 1.1.1.1 with the systemd-resolved service. To do this, you need to create a new file in the /etc/systemd/resolved.conf directory with the following contents:

[Resolve]
DNS=1.1.1.1 1.0.0.1

This will configure your Debian 12 VPS to use the 1.1.1.1 public DNS resolver.

Q: How do I troubleshoot DNS resolver issues in Debian 12?

A: To troubleshoot DNS resolver issues in Debian 12, you can use the following commands:

dig example.com
nslookup example.com
host example.com

These commands will display the DNS resolver settings that your Debian 12 VPS is using to resolve the example.com domain name. If you encounter any issues, you can check the system logs for errors related to the DNS resolver.

Q: Can I use a custom DNS resolver with the `resolvconf` service?

A: Yes, you can use a custom DNS resolver with the resolvconf service. To do this, you need to create a new file in the /etc/resolvconf/resolv.conf.d directory with the following contents:

nameserver 192.168.1.1
nameserver 192.168.1.2

This will configure your Debian 12 VPS to use the custom DNS resolver at 192.168.1.1 and 192.168.1.2.

Q: How do I reset the DNS resolver settings to their default values in Debian 12?

A: To reset the DNS resolver settings to their default values in Debian 12, you can use the following command:

sudo resolvconf -u

This will reset the DNS resolver settings to their default values.

Q: Can I use a DNS resolver with a custom port number in Debian 12?

A: Yes, you can use a DNS resolver with a custom port number in Debian 12. To do this, you need to create a new file in the /etc/resolvconf/resolv.conf.d directory with the following contents:

nameserver 192.168.1.1:5353
nameserver 192.168.1.2:5353

This will configure your Debian 12 VPS to use the custom DNS resolver at 192.168.1.1:5353 and 192.168.1.2:5353.

Q: How do I configure the DNS resolver to use a specific protocol (e.g., TCP or UDP) in Debian 12?

A: To configure the DNS resolver to use a specific protocol (e.g., TCP or UDP) in Debian 12, you need to create a new file in the /etc/systemd/resolved.conf directory with the following contents:

[Resolve]
DNS=1.1.1.1 1.0.0.1
DNSProtocol=tcp

This will configure your Debian 12 VPS to use the 1.1.1.1 public DNS resolver with TCP protocol.

Q: Can I use a DNS resolver with a custom timeout value in Debian 12?

A: Yes, you can use a DNS resolver with a custom timeout value in Debian 12. To do this, you need to create a new file in the /etc/systemd/resolved.conf directory with the following contents:

[Resolve]
DNS=1.1.1.1 1.0.0.1
DNSTimeout=10

This will configure your Debian 12 VPS to use the 1.1.1.1 public DNS resolver with a custom timeout value of 10 seconds.

Q: How do I configure the DNS resolver to use a specific DNS server for a specific domain name in Debian 12?

A: To configure the DNS resolver to use a specific DNS server for a specific domain name in Debian 12, you need to create a new file in the /etc/resolvconf/resolv.conf.d directory with the following contents:

nameserver 192.168.1.1 example.com
nameserver 192.168.1.2

This will configure your Debian 12 VPS to use the custom DNS resolver at 192.168.1.1 for the example.com domain name and the default DNS resolver for all other domain names.

Q: Can I use a DNS resolver with a custom search domain in Debian 12?

A: Yes, you can use a DNS resolver with a custom search domain in Debian 12. To do this, you need to create a new file in the /etc/resolvconf/resolv.conf.d directory with the following contents:

nameserver 192.168.1.1
search example.com

This will configure your Debian 12 VPS to use the custom DNS resolver at 192.168.1.1 and search for domain names in the example.com domain.

Q: How do I configure the DNS resolver to use a specific DNS server for a specific IP address in Debian 12?

A: To configure the DNS resolver to use a specific DNS server for a specific IP address in Debian 12, you need to create a new file in the /etc/resolvconf/resolv.conf.d directory with the following contents:

nameserver 192.168.1.1 192.168.1.100
nameserver 192.168.1.2

This will configure your Debian 12 VPS to use the custom DNS resolver at 192.168.1.1 for the IP address 192.168.1.100 and the default DNS resolver for all other IP addresses.

Q: Can I use a DNS resolver with a custom IP address in Debian 12?

A: Yes, you can use a DNS resolver with a custom IP address in Debian 12. To do this, you need to create a new file in the /etc/resolvconf/resolv.conf.d directory with the following contents:

nameserver 192.168.1.1

This will configure your Debian 12 VPS to use the custom DNS resolver at 192.168.1.1.

Q: How do I configure the DNS resolver to use a specific DNS server for a specific network interface in Debian 12?

A: To configure the DNS resolver to use a specific DNS server for a specific network interface in Debian 12, you need to create a new file in the /etc/resolvconf/resolv.conf.d directory with the following contents:

nameserver 192.168.1.1 eth0
nameserver 192.168.1.2

This will configure your Debian 12 VPS to use the custom DNS resolver at 192.168.1.1 for the eth0 network interface and the default DNS resolver for all other network interfaces.

Q: Can I use a DNS resolver with a custom port number for a specific network interface in Debian 12?

A: Yes, you can use a DNS resolver with a custom port number for a specific network interface in Debian 12. To do this, you need to create a new file in the /etc/resolvconf/resolv.conf.d directory with the following contents:

nameserver 192.168.1.1:5353 eth0
nameserver 192.168.1.2

This will configure your Debian 12 VPS to use the custom DNS resolver at 192.168.1.1:5353 for the