18 DNS Best Practices for DNS Security and Performance

In 2025, numerous cybersecurity threats have emerged, including DNS spoofing, cache poisoning, DNS tunneling, DNS hijacking, and AI-driven DNS attacks.

The Domain Name System (DNS) is often overlooked in network infrastructure until a catastrophic failure exposes its critical role.

The Domain Name System (DNS) is a foundational component of internet infrastructure. It translates human-readable domain names into IP addresses that computers use to locate and communicate with each other. Despite its critical role, DNS security and performance optimization are frequently neglected in organizational IT strategies.

This guide outlines 18 best practices to help you protect and optimize your DNS operations.

18 Best Practices for DNS Security and Performance

The following 18 best practices for ensuring the security of DNS stem from my experience as system administrator and discussions with other experienced sysadmins.

Maintain DNS Redundancy and High Availability

Redundancy is a critical functional requirement because when the DNS service is unavailable or performs poorly, users will be able to find and connect to your online resources (websites, applications, email servers, file servers, etc.) associated with your domain.

Building high availability in this context means you need to deploy multiple DNS servers, including both primary and secondary servers, in geographically diverse locations and network segments. Additionally, configure high-availability clusters with automatic failover capabilities for uninterrupted DNS service.

Restrict Access to DNS Servers Information

Disclosing the DNS server software version, operating system, and network topology can help attackers target your server and cause cybersecurity issues.

The less information DNS servers expose, the fewer opportunities attackers have to exploit vulnerabilities through a custom-built tool.

Start by limiting zone transfers to authorized servers only. Additionally, implement proper access controls, and use encryption for transfer security. Finally, you should make sure that only trusted administrators have access to DNS configuration.

Use Internal DNS Servers for Private Queries

Using public DNS servers, especially for internal DNS queries, can cause security and privacy issues, like leakage of sensitive internal network information. You can easily solve the issues by setting up a separate internal DNS server to handle internal organizational queries. This separation creates an additional security boundary between the internal network and the public internet.

Use Local or Closest DNS Servers

As the physical distance between your device and the DNS server increases, the greater the chance of latency and performance issues. 

By reducing the geographical distance between the server and the device, DNS queries will be resolved faster, and the user experience will be improved. Additionally, I recommend using Anycast routing to automatically direct queries to the nearest available DNS server in your infrastructure.

Enable DNS Logging and Monitoring

DNS is a prime target for attackers because minor attacks can cause potentially huge disruptions in business operations. 

I strongly suggest using DNS logging and monitoring to keep a check on high CPU usage, memory pressure, failed queries, and responses. This simple exercise helps you detect anomalies, potential attacks, or misconfiguration issues and resolve them quickly.

Lock DNS Cache

Locking the DNS cache is necessary to prevent DNS cache poisoning. DNS cache poisoning or DNS spoofing is where malicious or incorrect data is injected into a DNS resolver’s cache. These entries can redirect users to fraudulent or malicious websites.

By implementing a cache locking mechanism, you prevent attackers from injecting malicious DNS records that could redirect users to fraudulent websites.

Filter Requests 

Filtering DNS requests is one of the primary security methods to protect against redirection to malicious or phishing sites, command-and-control servers, and other threat sources. 

Organizations can also implement DNS filtering to prevent access to any inappropriate content and sites. 

Filtering DNS requests adds a crucial security layer to prevent malware communications and data exfiltration. 

Use DNS over HTTPS (DoH) or DNS over TLS (DoT)

Traditional DNS queries are sent in plain text. Attackers usually exploit this loophole for man-in-the-middle attacks. DoH/DoT makes it harder for attackers to monitor activities by encrypting your DNS queries. In addition, the encrypted queries also make it difficult to tamper with the queries and poison your DNS cache. 

I always recommend encrypting DNS traffic to prevent eavesdropping, tampering, and man-in-the-middle attacks. Both DoH and DoT ensure the privacy and integrity of DNS communications between clients and resolvers.

DNS Firewalls

Deploying DNS firewalls establishes an extra layer of security. A DNS firewall is a dedicated security component in the DNS resolution layer that inspects and controls how DNS traffic is directed within the infrastructure.

A DNS firewall operates at the domain name lookup as the very first step of an internet connection. 

These firewalls compare the domain name with the list of known malicious domains, and prevent the connection even before an attack is initiated. It protects against data migration, security compromises, and also provides detailed logs on blocked threats and attempted connections by malicious sites.

Keep DNS Server Software Up-to-Date

If you implement all security measures but do not keep your server software up-to-date, all your efforts are essentially in vain.

All software, especially complex network daemons like DNS servers, can have security bugs or vulnerabilities. Once the vulnerabilities are found by attackers, they can find ways to exploit them. This is why the vendors release new updates regularly to fix the issue. 

Keeping the software up-to-date is not just about security, but it also improves performance, stability, and adds new features. Therefore, ensure a systematic process for tracking, testing, and deploying updates across your DNS infrastructure.

Mask the Primary DNS Server and Information

The primary DNS server holds a copy of your zone files, which contain all the domain records. By masking the primary DNS server and information, you prevent the attacker from altering DNS records, redirecting website traffic to any malicious sites, and identifying how primary and secondary servers interact or identify dependencies.

You can implement response policy zones (RPZ) to control what information is shared.

Validate DNS Data Integrity with DNSSEC

In traditional DNS, there is no way for a user to understand whether the search result they received has been tampered with. Attackers exploit this and redirect the users to a malicious site by forging the cache.

DNSSEC (Domain Name System Security Extensions) cryptographically verifies that the data has not been tampered with and is sent by a legitimate authoritative zone publisher.

Implement Rate Limiting

Attackers often target DNS servers with query floods, sending a massive number of requests to consume all the server’s resources, including memory and network bandwidth. At times, this massive number of requests can also happen when a client or an application accidentally generates requests. 

Setting up rate limiting helps avoid this risk. This set of rules limits the number of queries from a single source IP address, and/or within a specific time frame. By implementing rate limiting, DNS amplification attacks and resource exhaustion from query floods can be prevented.

Separate Authoritative and Recursive DNS Servers

Authoritative and recursive DNS servers are two types of servers with different functions. By separating them architecturally, you can improve the security and performance.

Authoritative servers hold the zone file, and recursive servers handle queries. When you combine both servers, the attack meant for the authoritative server can also affect the recursive server and vice versa. 

For this reason, I always recommend separating authoritative and recursive DNS servers.

Implement DDoS Protection

Attackers know that hitting DNS is highly impactful. DNS can be attacked through various methods like query flooding and spoofing, causing service outage, financial loss, data loss, and more. 

By implementing DDoS protection, you can mitigate DNS-specific attack vectors. You can consider cloud-based DNS services for built-in DDoS protection.

Perform Periodic Testing

Conducting regular security assessments, penetration tests, and performance benchmarks of your DNS infrastructure helps you understand the impact of any potential threats and issues.

Periodic testing reveals any misconfigurations, measures query response times, checks the implemented security measures, their resilience to any attacks, and more. You can mitigate any potential issues and resolve problems that need fixing by checking DNS servers periodically.

Create Backups

Creating backups is a non-negotiable practice for disaster recovery and ensuring business continuity.

If the DNS server or zone files get corrupted for any reason, it can affect your services. However, if the data is backed up appropriately, you can quickly restore and reduce the downtime. 

Facilitate Random DNS Socket Pool Utilization

This is a technique where the user uses a random source port from a large pool of available ephemeral ports to connect. When the query is sent from a specific source port on the resolver, it is quite predictable for attackers to attempt spoofing. Now, when the resolver uses a random port, the attacker needs to guess the right port from the thousands of possible source ports. This makes attacking much harder.

Conclusion 

With the rising rate of cyber attacks, implementing these practices is essential to maintaining a secure and resilient DNS infrastructure. Organizations should implement these practices based on their specific needs and risk assessment while maintaining focus on core security requirements.

FAQs

Why is DNS security important for enterprise networks?

DNS security is crucial because DNS is often a target for cyberattacks like DNS spoofing, cache poisoning, and DDoS attacks. Without proper DNS protection, attackers can redirect traffic, steal data, or bring down critical services. Implementing DNS best practices helps safeguard your network’s integrity and ensure secure communication across systems.

What are some common DNS misconfigurations that impact performance?

Some common DNS misconfigurations include overly long TTL (Time to Live) values, using a single DNS server without redundancy, or failing to block open recursive resolvers. These issues can lead to slow resolution times, higher latency, and even DNS outages. Following DNS performance best practices minimizes these risks and ensures faster, more reliable responses.

How does DNS caching improve performance and security?

DNS caching reduces the number of external DNS lookups by storing previous query results locally, which speeds up access and reduces bandwidth. From a security standpoint, well-configured caching helps mitigate DNS-based attacks by limiting exposure to external queries. Regular cache management is key to balancing performance and protection.

What DNS best practices should small businesses follow to stay secure?

Small businesses should enable DNSSEC (DNS Security Extensions), use reputable DNS providers, configure firewalls to restrict unauthorized DNS traffic, and monitor for unusual DNS query patterns. These basic DNS security practices significantly reduce the risk of compromise, even with limited IT resources.

Can switching DNS providers improve both security and performance?

Yes, switching to a DNS provider that offers advanced features like threat intelligence, built-in DDoS protection, and global anycast networks can greatly enhance both DNS performance and security. Providers like Cloudflare, Google DNS, and Quad9 are known for offering high-speed resolution with robust protection against common DNS threats.