Unbound Stub-zone Not Working

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Introduction

Unbound is a popular, open-source, caching DNS resolver that provides a high-performance and secure way to resolve domain names. One of the key features of Unbound is its ability to handle stub-zones, which allow it to resolve local data without the need for a full DNS server. However, sometimes, the stub-zone may not work as expected, leading to issues with resolving local data. In this article, we will discuss the common issues that may cause an Unbound stub-zone not to work and provide a step-by-step guide to troubleshoot and resolve the problem.

Understanding Unbound Stub-Zone

Before we dive into the troubleshooting process, let's understand what a stub-zone is and how it works. A stub-zone is a type of DNS zone that contains a limited set of records, typically for local data. Unbound uses stub-zones to resolve local data without the need for a full DNS server. When a query is received, Unbound checks the stub-zone to see if the record is present. If it is, Unbound returns the record; otherwise, it forwards the query to the upstream DNS server.

Common Issues with Unbound Stub-Zone

There are several common issues that may cause an Unbound stub-zone not to work. Some of the most common issues include:

  • Incorrect configuration: The most common issue is incorrect configuration. Make sure that the stub-zone is properly configured in the Unbound configuration file.
  • Missing or incorrect records: If the records are missing or incorrect, Unbound will not be able to resolve the local data.
  • DNSSEC issues: DNSSEC (Domain Name System Security Extensions) is a security protocol that helps to prevent DNS spoofing. However, DNSSEC can also cause issues with stub-zones if not properly configured.
  • Cache issues: Unbound uses a cache to store resolved records. However, cache issues can cause problems with stub-zones.

Troubleshooting Unbound Stub-Zone

To troubleshoot Unbound stub-zone issues, follow these steps:

Step 1: Check the Unbound Configuration File

The first step is to check the Unbound configuration file to ensure that the stub-zone is properly configured. The configuration file is usually located at /etc/unbound/unbound.conf (on Linux systems). Open the file and look for the stub-zone section. Make sure that the stub-zone is properly configured with the correct domain name and records.

Step 2: Check the Records

The next step is to check the records in the stub-zone. Make sure that the records are present and correct. You can use the dig command to check the records. For example:

dig @localhost host1.wireguard

This command will check the record for host1.wireguard on the local Unbound server.

Step 3: Check DNSSEC

If you are using DNSSEC, make sure that it is properly configured. You can check the DNSSEC configuration by running the following command:

unbound-control -c /etc/unbound/unbound.conf stats

This command will display the DNSSEC statistics.

Step 4: Check the Cache

, check the cache to ensure that it is working correctly. You can check the cache by running the following command:

unbound-control -c /etc/unbound/unbound.conf cache

This command will display the cache statistics.

Resolving Unbound Stub-Zone Issues

If you have followed the troubleshooting steps and still encounter issues with the Unbound stub-zone, here are some additional steps you can take to resolve the problem:

  • Restart the Unbound service: Sometimes, simply restarting the Unbound service can resolve the issue.
  • Check the Unbound logs: Check the Unbound logs to see if there are any error messages that may indicate the cause of the issue.
  • Check the DNS server logs: Check the DNS server logs to see if there are any error messages that may indicate the cause of the issue.
  • Check the network configuration: Check the network configuration to ensure that the Unbound server is properly configured.

Conclusion

In conclusion, Unbound stub-zone issues can be frustrating to troubleshoot and resolve. However, by following the steps outlined in this article, you should be able to identify and resolve the issue. Remember to check the Unbound configuration file, records, DNSSEC, and cache to ensure that they are working correctly. If you are still encountering issues, restart the Unbound service, check the Unbound logs, and check the DNS server logs.

Additional Resources

For additional resources on Unbound and stub-zones, check out the following:

  • Unbound documentation: The official Unbound documentation provides detailed information on configuring and troubleshooting Unbound.
  • Stub-zone documentation: The official stub-zone documentation provides detailed information on configuring and troubleshooting stub-zones.
  • Unbound community forum: The Unbound community forum is a great place to ask questions and get help from other Unbound users.

Polling it ...

To poll the Unbound server and check the stub-zone, you can use the following command:

dig @localhost host1.wireguard

This command will check the record for host1.wireguard on the local Unbound server.

Example Use Case

Here is an example use case for Unbound stub-zone:

Suppose you have a VPN server that uses the wireguard domain. You want to resolve the VPN server addresses using the Unbound stub-zone. You can configure the Unbound stub-zone as follows:

local-data: "host1.wireguard. A 10.10.100.10"
local-data: "host2.wireguard. A 10.100.100.11"

This configuration will allow the Unbound server to resolve the VPN server addresses using the stub-zone.

Conclusion

Frequently Asked Questions

In this article, we will answer some of the most frequently asked questions about Unbound stub-zones.

Q: What is a stub-zone?

A: A stub-zone is a type of DNS zone that contains a limited set of records, typically for local data. Unbound uses stub-zones to resolve local data without the need for a full DNS server.

Q: How do I configure a stub-zone in Unbound?

A: To configure a stub-zone in Unbound, you need to add the following lines to your Unbound configuration file:

stub-zone:
    name: "wireguard"
    stub-addr: 127.0.0.1@5353

You also need to add the following lines to your Unbound configuration file to specify the records for the stub-zone:

local-data: "host1.wireguard. A 10.10.100.10"
local-data: "host2.wireguard. A 10.100.100.11"

Q: What is the difference between a stub-zone and a forward-zone?

A: A stub-zone is a type of DNS zone that contains a limited set of records, typically for local data. A forward-zone, on the other hand, is a type of DNS zone that contains a full set of records for a domain. Unbound uses stub-zones to resolve local data without the need for a full DNS server, while forward-zones are used to forward queries to an upstream DNS server.

Q: Can I use a stub-zone with a forward-zone?

A: Yes, you can use a stub-zone with a forward-zone. In fact, this is a common configuration for Unbound. The stub-zone is used to resolve local data, while the forward-zone is used to forward queries to an upstream DNS server.

Q: How do I troubleshoot a stub-zone issue?

A: To troubleshoot a stub-zone issue, you can follow these steps:

  1. Check the Unbound configuration file to ensure that the stub-zone is properly configured.
  2. Check the records in the stub-zone to ensure that they are present and correct.
  3. Check the DNSSEC configuration to ensure that it is properly configured.
  4. Check the cache to ensure that it is working correctly.
  5. Restart the Unbound service to ensure that the changes take effect.

Q: Can I use a stub-zone with a VPN?

A: Yes, you can use a stub-zone with a VPN. In fact, this is a common configuration for Unbound. The stub-zone is used to resolve local data, while the VPN is used to encrypt the data.

Q: How do I configure a stub-zone with a VPN?

A: To configure a stub-zone with a VPN, you need to add the following lines to your Unbound configuration file:

stub-zone:
    name: "vpn"
    stub-addr: 127.0.0.1@5353

You also need to add the following lines to your Unbound configuration file to specify the records for the stub-zone:

local-data: "host1pn. A 10.10.100.10"
local-data: "host2.vpn. A 10.100.100.11"

Q: Can I use a stub-zone with a cloud provider?

A: Yes, you can use a stub-zone with a cloud provider. In fact, this is a common configuration for Unbound. The stub-zone is used to resolve local data, while the cloud provider is used to host the data.

Q: How do I configure a stub-zone with a cloud provider?

A: To configure a stub-zone with a cloud provider, you need to add the following lines to your Unbound configuration file:

stub-zone:
    name: "cloud"
    stub-addr: 127.0.0.1@5353

You also need to add the following lines to your Unbound configuration file to specify the records for the stub-zone:

local-data: "host1.cloud. A 10.10.100.10"
local-data: "host2.cloud. A 10.100.100.11"

Conclusion

In conclusion, Unbound stub-zones are a powerful tool for resolving local data without the need for a full DNS server. By following the steps outlined in this article, you should be able to configure and troubleshoot a stub-zone with ease. Remember to check the Unbound configuration file, records, DNSSEC, and cache to ensure that they are working correctly. If you are still encountering issues, restart the Unbound service, check the Unbound logs, and check the DNS server logs.