How Do I Harden My DNS Server?


Angela Bailey

In this tutorial, we will explore the steps to harden your DNS server. Strengthening the security of your DNS server is essential to protect it from potential attacks and ensure the integrity of your network. Follow these guidelines to enhance the security of your DNS server:

1. Update Your DNS Software Regularly

Keeping your DNS software up to date is crucial for maintaining a secure server.

Updates often include security patches that address vulnerabilities discovered over time. Ensure that you regularly check for updates and apply them promptly.

2. Configure Access Control Lists (ACLs)

Implementing Access Control Lists (ACLs) is an effective way to control who can access your DNS server and what actions they can perform. By defining specific rules and restrictions, you can minimize the risk of unauthorized access or malicious activities.

2.1 Restrict Zone Transfers

To prevent unauthorized zone transfers, configure ACLs to allow only trusted servers to request zone transfers. This ensures that sensitive information about your domain is not leaked to unauthorized parties.2 Limit Recursive Queries

Limiting recursive queries helps protect against recursive query attacks, where an attacker exploits the DNS server’s resources by initiating a large number of recursive queries. Restrict recursive queries only to authorized clients or networks.

3. Implement Rate Limiting

Rate limiting can be employed to mitigate Denial-of-Service (DoS) attacks Targeting your DNS server by limiting the number of queries accepted from a particular IP address within a specified time frame.

4. Enable Query Logging

Enabling query logging allows you to monitor and analyze DNS traffic, helping you identify any suspicious activities or potential security breaches. Regularly reviewing and analyzing log files can provide valuable insights into the overall security of your DNS server.


DNS Security Extensions (DNSSEC) adds an extra layer of security to your DNS server by validating the authenticity and integrity of DNS responses. Implementing DNSSEC ensures that clients receive legitimate responses and are protected against DNS spoofing attacks.

6. Enable DoT or DoH

DNS over TLS (DoT) and DNS over HTTPS (DoH) protocols encrypt DNS queries and responses, making it harder for attackers to intercept or manipulate the communication between client and server. Enabling DoT or DoH further enhances the security of your DNS server.

7. Monitor and Analyze Traffic

Regularly monitor and analyze your DNS server’s traffic patterns to identify any unusual or suspicious behavior. Implementing intrusion detection systems (IDS) or using dedicated monitoring tools can help you detect potential threats promptly.

8. Regularly Backup Your Zone Files

To mitigate the risk of data loss or corruption, regularly back up your zone files. In case of a security incident or hardware failure, having up-to-date backups ensures that you can quickly restore your DNS server to its previous state without significant disruptions.


Harden your DNS server by following these best practices to safeguard it from potential attacks, enhance its security, and ensure uninterrupted network functionality. Regularly review and update your security measures to stay ahead of evolving threats in the ever-changing cybersecurity landscape.

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