Top DNS Security Best Practices



Top DNS Security Best Practices- Since the service has grown crucial to practically all operations involving networked applications, DNS security best practises are critical for all enterprises. It allows networked apps to communicate more easily. DNS has also grown in complexity, both in terms of implementation and theory.

Meanwhile, cyber attackers are increasingly focusing their efforts on DNS infrastructure. When the DNS service is down, apps are unable to interact, which might result in critical processes being halted. DNS security best practises are important for maintaining the DNS infrastructure’s availability and health.

The DNS Security Best Practices listed below can help guarantee DNS has a stable performance and is secure.

Ensure DNS logs all activities – One of the most important DNS Security Best Practices

DNS logging is recommended by security experts as a useful approach for monitoring DNS actions and occurrences. DNS logs can reveal whether criminal individuals are attempting to interfere with DNS servers. DNS debug logs, in addition to client actions, are used to identify existing issues with DNS updates or queries.

Furthermore, DNS exposes any indications of cache poisoning. A cyber attacker alters the data stored in the DNS cache to target clients with malicious inputs in this scenario. Changing a respectable website’s IP address to that of a malicious website, for example, may cause the DNS server to redirect customers to malware-infested websites.

Such activities have the potential to jeopardise a company’s security. While DNS debug logging is essential for DNS security, some system administrators may turn it off to improve efficiency. Monitoring network activity ensures that attacks, such as Distributed Denial of Service (DDoS) attempts, are detected quickly.

Lock the DNS cache

The DNS finds a client’s query information and saves it in a cache for future use as a reference. When the client makes the same queries repeatedly, the procedure improves the DNS servers’ response time.

Cybercriminals, on the other hand, can use the feature to change data that has already been stored. The DNS cache must be locked in order for the DNS debugging log functionality to function properly. This recommended practise allows system administrators to identify when cached data should be changed. The DNS server only saves lookup information for the time period indicated in the time to live setting (TTL).



When the cache lock is disabled, the store information can be updated or replaced before the TTL expires, allowing cache poisoning attacks to take place. Companies can choose to enable default cache locking depending on the operating systems they use. The locking cache’s scale can be set to 100 percent to prevent the cache information from being changed until the TTL expires.

Enable DNS filtering

DNS filtering is a reliable strategy for preventing people from accessing harmful domains or websites. It allows system administrators to prevent domain or site name resolutions that are known to contain dangerous information. If a client sends a query requesting access to a prohibited domain, the DNS server disconnects all communications immediately.

As a result, DNS filtering dramatically reduces the risk of malware and viruses infiltrating an organization’s network. When a client is unable to access a restricted, harmful URL, the security control protects IT infrastructure from potential security concerns. As a result, IT security specialists are no longer required to wipe up dangerous viruses on a regular basis.

Additionally, in accordance with existing IT standards, a corporation may seek to restrict specific domains. To guarantee that staff remain extremely productive, many companies, for example, restrict certain websites. Video streaming, illegal content, social media, and gambling sites are all examples of such domains. DNS queries can be filtered by groups or individual users, or all users might be blocked from accessing specified domains.

Modern firewalls and software security solutions usually include standardised DNS filtering. Companies that use such appliances gain access to frequently updated lists of dangerous sites. Organizations can use automated DNS filtering to eliminate the time-consuming and inefficient human entries.

Use DNSSEC to validate the integrity of DNS data

Clients can receive only valid responses to their requests thanks to the Domain Name System Security Extensions (DNSSEC). DNSSEC ensures the integrity of DNS data provided to name servers by digitally signing it. When a client sends a query request, the DNS server checks to see if the response has a valid digital signature, which informs the client that the information received is reliable. DNSSEC is an extra layer of security that helps guard against DNS protocol attacks.

Furthermore, because DNSSEC ensures origin authority and data integrity, threats like cache poisoning and DNS spoofing can be successfully avoided. As a result, clients may rest assured that they are visiting the correct pages.

Ensure accurate configuration of access control lists

To protect DNS servers against spoofing attacks and illegal access attempts, access control lists are essential. Only system and IT administrators have access to the principal DNS servers in order to keep them secure. Only legitimate clients can communicate with DNS servers thanks to accurate access control list configurations that allow a specified host to connect to them.

Furthermore, access control lists should specify which servers are allowed to do zone transfers. Cyber attackers may try to determine the organisational network zone layout by sending zone transfer requests to secondary DNS servers. Cybercriminals are prevented from accessing zone information by blocking zone transfer requests made through a secondary DNS server. The configurations are critical because they prevent harmful or unauthorised third parties from deciphering the internal network’s organisation.

Separate authoritative from recursive name servers

To find a name and its IP address, an authoritative name server searches only the local database. Recursive name servers, on the other hand, search a hierarchy of extra name servers on top of the local database to find a name and its IP addresses.



To isolate and divide roles based on the network’s logical perspectives, companies should utilise different recursive and authoritative name server machines. System administrators must also configure authoritative name servers so that they can only communicate DNS changes to other authoritative name servers. Because authoritative name servers lack caching capabilities, database entries that are corrupted or fraudulent can have far-reaching consequences.

Use Anycast to enable forwarding routers to redirect DNS queries

Routers employ Anycast to allow numerous servers to share IP addresses and transmit network traffic and messages to the most important server rather than a single server. Anycast is used by name servers to show resilience, lessen the effects of a DDoS attack, and share a workload.

Anycast improves a network’s resiliency by allowing routers to dynamically and flexible redirect traffic to the closest yet available server. Anycast transfers traffic to the nearest accessible server if a firm disconnects a server from its network. As a result, the method expands a system’s surface area. The network element is vulnerable to security risks and attacks, thus traffic is dispersed over multiple servers to mitigate the impact of a DDoS attack.

Deploy dedicated DNS appliances

DNS applications, like other network appliances, are constructed with a specific function in mind. As a result, both software and hardware are set up to maximise performance, manageability, and security. The capabilities and levels of tuning available in dedicated DNS appliances are not available on standard operating system servers. The advantages of establishing dedicated DNS applications are comparable to those of implementing other network appliances, such as maximising RAM availability, limiting driver requirements, limiting network chatter on interfaces, and limiting unneeded ports.

In summary, leveraging the usage of purpose-driven appliances in DNS design allows for the removal of all extraneous protocols, drivers, and applications, reducing the attack surface dramatically. Security elements such as logging and monitoring can now be focused on certain protocols and services thanks to the targeted functionality. Audit logging, change monitoring, and user management can also be considerably improved and focused to essential security capabilities.

Update the DNS server regularly

Cyber enemies will always try to take advantage of the DNS server software’s security flaws. Because it allows attackers to utilise the DNS server for data exfiltration and command and control attacks, DNS is a great target for attacks. The dangers emphasise the importance of keeping DNS server software up to date in order to avoid attacks.

However, because the procedure is done per-server, the autonomous server design can make it difficult to apply timely upgrades and security updates. Using a centrally controlled method to install architecture-wide upgrades is the ideal strategy. Furthermore, because DNS servers are robust and do not issue warnings when they are out of current, businesses must be proactive in applying security patches.

Ensure the recursive DNS queries have response time limits

Response rate limiting should be used to throttle the speed with which authoritative name servers answer to queries coming from a certain IP address. Response rate restriction is supported by most name server programmes, including NSD, Knot, and Bind 9.6.4 or later. A name server utilises response rate limitation to keep track of how many times it has given the same answer to the same query.

The name server takes slower to respond after the rate surpasses the pre-configured level. As a result, the name server won’t be able to respond to queries any faster than the configured limit. A name server that complies with response rate limiting is thus immune to many sorts of DDoS attacks.

Hide the primary DNS server

The organization’s primary DNS server should be hidden from public view, according to system administrators. As a result, they should set up the DNS servers that are visible to the public as slaves, while the principal DNS server should be set up as a master name server that is not visible to the public.

The NS entries are not recorded in a DNS database accessible to the public by a hidden or stealth master name server. Only the slave name servers are accessible to the general public. The slave and stealthy master architecture prevents zone or query transfer from exposing the name servers to the public. Furthermore, because only the hidden master server can upgrade slave name servers via the push operation, the architecture maintains the integrity of the DNS databases of the slave name servers.

Configure the DNS socket pool

For DNS lookups, the DNS socket pool allows the DNS server to use randomised source ports. Using random ports allows the DNS server to select a source port at random from a pool of idle sockets. Instead of using the same port for many operations, the DNS server chooses a random port from the pool, making it more difficult to identify the source port for source port DNS requests. By default, several operating systems support the setup.

Harden the name servers

Only the name server software and the installed operating system should be operated on the name server workstations. The name server machine should also play a specialised function in network activity support. Hacktivists will be attracted to the name server PC if you install additional software.

Furthermore, additional software can reduce the performance of the name server machine and, if bugs are present, can cause it to crash. On the same note, a name server’s only connection should be the network link for obtaining updates and responding to DNS queries. The attack surface is increased by adding more network cables or opening ports.

Ensure DNS high availability and redundancy

Because the DNS serves as the communication backbone for network applications, it must be available 24 hours a day, seven days a week. Organizations should operate at least a backup and primary DNS server within the firm to achieve the necessary redundancy. Furthermore, deploying two servers, at the absolute least, can ensure that business-critical operations continue uninterrupted.

DNS operations are required for critical services such as email, file sharing, and active directory services. Internal DNS servers that are redundant, high-availability, functional, and healthy ensure that internal applications and devices interact continually.

Summary of DNS Security Best Practices

By following these DNS security best practises, your company will be effectively protected against hackers that may target DNS. Do you have any suggestions for DNS Security Best Practices to add to this list? Please let me know by leaving a comment.

Jennifer Thomas
Jennifer Thomas is the Co-founder and Chief Business Development Officer at Cybers Guards. Prior to that, She was responsible for leading its Cyber Security Practice and Cyber Security Operations Center, which provided managed security services.