Tap into these 10 best practices for DNS security

In today's digital age, the Domain Name System (DNS) stands as the often overlooked keystone of the internet. It's the silent force that translates human-friendly domain names into machine-readable IP addresses, ensuring seamless online communication. And it remains imperative to stay on top of your DNS best practices. 

DNS security is something you should never take lightly: Disruption of DNS security has a median cost of $70,000 and a mean of $2.8 million. If you can get ahead of the problems these threats post, you can save thousands. 

In this blog, we’ll go into the top DNS security best practices, from the significance of redundancy to the art of DNS filtering. We'll explore why separating your authoritative and recursive DNS servers is a game-changer, and why setting limits on recursive DNS queries is a masterstroke in balancing speed and security.

The importance of using DNS best practices

Let’s start with the basics.

Your DNS is the backbone of computer networking, acting as the translator between human-readable domain names and IP addresses. Without DNS, the seamless communication we've come to rely on in our interconnected world would come to a standstill. 

A misconfigured DNS can lead to a myriad of issues, including authentication failures and replication problems. For this reason, among many others, you need to stay on top of your DNS best practices.

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The top 10 DNS security best practices

1. Have at least two internal DNS servers.

One of the foundational best practices in DNS security is the principle of redundancy. Why? Because DNS and AD are the lifeblood of most IT infrastructures. Their failure can lead to catastrophic disruptions, affecting everything from internet browsing to accessing vital cloud applications.

Active Directory, which is central to many organizational IT structures, is heavily reliant on DNS. In fact, the entire functionality of an Active Directory domain hinges on the seamless operation of DNS.

In the event that the primary DNS (DC1/DNS) encounters a failure, clients automatically switch to the secondary DNS. This ensures uninterrupted access to essential resources like emails, applications, and the internet. Without this secondary internal DNS, the consequences can be dire.

2. Block malicious domains with DNS filtering.

DNS filtering serves a primary purpose: it prevents users within your network from accessing specific websites or domains. But why would you want to block certain domains? The answer is straightforward: many domains are known to be malicious. By blocking them, you're proactively safeguarding your network.

When a client within your network tries to access a blocked website, the DNS server immediately halts the communication. It drastically reduces the chances of viruses and malware infiltrating your network. By preventing clients from accessing malicious sites, you minimize potential threats at the source.

The what	Why DNS security matters
Business continuity	DNS attacks can disrupt online services, leading to downtime and loss of revenue.
Data protection	DNS vulnerabilities can expose sensitive business data to cybercriminals.
Regulatory compliance	Many industries have regulations requiring businesses to ensure data security.
Customer trust	Customers expect their data to be secure; breaches can lead to loss of clientele.
Operational efficiency	A secure DNS ensures smooth business operations without disruptions.

3. DNS order on domain controllers.

For your organization's optimal performance and security, understanding the importance of DNS order on domain controllers is crucial.

When setting up your domain controllers, your primary DNS should point to another Domain Controller (DC) within the same site. As for the secondary DNS, it should be set to the domain controller itself, using the loopback address. Why is this important?

This setup not only enhances the performance of your DNS servers but also ensures their availability. If you were to point the primary DNS to itself from the outset, it could result in unnecessary delays. 

For you, this means smoother operations, reduced downtime, and a more resilient infrastructure. Always prioritize this DNS order for the best outcomes for your organization.

4. Set up aging and scavenging of DNS records.

Here's why it matters to you: DNS aging and scavenging is a two-part process designed to automate the management of your DNS records. The first part, aging, applies a timestamp to any newly created DNS records. This timestamp serves as a marker, indicating when the record was last active. The second part, scavenging, acts as a cleaner. 

It periodically scans and removes any DNS records with timestamps that are deemed outdated based on a predetermined time frame.

Now, consider the dynamic nature of your network. Computers within your organization might register multiple DNS entries due to various reasons - perhaps they've been relocated or something else has occurred. These multiple entries can lead to name resolution problems and connectivity issues, disrupting operations.

By enabling DNS aging and scavenging, you proactively address these challenges, ensuring that only relevant DNS records are retained.

Discover more ways to protect your DNS with our blog:

How UltraDNS can protect against a new wave of attacks Simplifying DNS management and automation with HashiCorp and UltraDNS Learning Insights: DNS security test

5. Set up PTR records.

DNS pointer records (PTR records) serve a fundamental function: they resolve an IP address back to its associated hostname. Think of it as a reverse directory, helping you identify which domain name is linked to a specific IP address. 

One of the primary advantages of PTR records is their role in troubleshooting. When issues arise, having a clear mapping between IP addresses and hostnames can significantly expedite the resolution process. 

Moreover, they play a vital role in enhancing your network's security. With PTR records in place, you can quickly identify and verify any unfamiliar or suspicious IP addresses.

6. Separate your authoritative and recursive DNS servers.

The authoritative name server is your trusted source. It scans only its local database, pinpointing a name and its corresponding IP address with unwavering accuracy. 

On the other hand, the recursive name server is the relentless seeker. It doesn't just rely on its local database; it ventures out, searching through a hierarchy of additional name servers to identify a name and its corresponding IP addresses.

For companies like yours, best practices dictate a clear separation of powers: use distinct machines for recursive and authoritative name servers. This approach allows you to isolate and differentiate roles based on your network's logical views, ensuring streamlined operations and enhanced security.

Tip: Configure your authoritative name servers to accept DNS updates solely from their authoritative counterparts. Authoritative name servers, while precise, lack caching capabilities. Any corrupted or fraudulent database entries can cascade into widespread issues, jeopardizing your digital operations.

7. Make sure your recursive DNS queries have limits on response time.

When it comes to DNS, unchecked speed can be a vulnerability. Enter the concept of limiting the response time for recursive DNS queries—a strategic move to ensure both performance and protection.

The core purpose of this practice is to regulate the pace at which authoritative name servers respond to queries from specific IP addresses.

How does it work? Name servers are equipped with a memory of sorts. They recall the frequency of their responses with the same answer to a consistent querier. 

But here's the catch: if this response rate breaches a pre-set threshold, the name server doesn't just continue at its usual pace. Instead, it deliberately delays its response, ensuring it doesn't answer queries faster than the established limit.

8. Validate your DNS data with DNSSEC.

DNSSEC, at its core, is designed to ensure that clients receive only valid responses to their queries. But how does it achieve this? It digitally signs DNS data sent to name servers, ensuring the integrity of the information.

When you, as a client, make a query, the DNS server doesn't just provide a response; it verifies the digital signature of that response. This process alerts you about the trustworthiness of the information you receive, acting as a gatekeeper between you and potential threats.

Your DNSSEC acts as a robust added security layer, specifically designed to counteract DNS protocol attacks. With DNSSEC in place, you're protected against malicious attacks like cache poisoning and DNS spoofing. It provides both origin authority and data integrity, ensuring that the information you receive is both genuine and unaltered.

By adhering to response rate limiting, name servers fortify themselves against a range of DDoS attacks, striking a balance between rapid service and robust security.

9. Make sure the configuration of your access control lists is accurate.

One of the cornerstones of network security is the accurate configuration of access control lists (ACLs). As one of the leading DNS server security best practices, ACLs play a pivotal role in protecting your DNS servers from potential threats, such as spoofing attacks and unauthorized access.

Proper ACL configurations act as the gatekeepers, ensuring that only legitimate clients communicate with your DNS servers. This selective access is your first line of defense against potential breaches.

ACLs also play a crucial role in zone transfer protections. ACLs meticulously specify which servers are allowed to conduct zone transfers. Threat actors often target secondary DNS servers, requesting zone transfers to reveal your network zone setups. 

By blocking such requests via secondary DNS servers, ACLs stop these cybercriminals in their tracks, preventing them from accessing vital zone details.

How Vercara can help.

With the myriad of threats lurking in the shadows, where do you begin? The answer lies in adopting DNS security best practices. And who better to guide you on this journey than Vercara?

Vercara brings to the table three industry-recognized solutions, bundled together to offer you unparalleled protection. As a trusted vendor with specialized expertise, our aim is to not only safeguard your online assets but also to lower your total cost of ownership.

Our offerings include:

• UltraDNS/UltraDNS²: Ensuring the availability and integrity of your online presence.
• UltraDDoS Protect: Shielding you from DDoS attacks targeting your DNS, applications, and infrastructure.
• UltraWAF: A robust web application firewall designed to protect your online web resources.

But that's not all. With Vercara, you also benefit from our 24x7x365 SOC and support, initial WAF setup, authoritative DNS, and DDoS protection for both applications and infrastructure. Our solutions are designed to protect your brand reputation, ensure uninterrupted access to your online assets, and deliver fast and accurate query responses.

Ready to fortify your digital defenses? 

Contact us today. It’s time to secure your digital future.