DNS scavenging is the process of removing stale DNS records, usually used together with DNS aging in order to free up space and improve system performance. In cybersecurity, in particular, DNS scavenging can help prevent DNS cache poisoning attacks and even reduce the chances of DNS servers being used in DDoS attacks.

In this article we will explore the process of DNS scavenging, how it works, how to enable it, what are its benefits and why is it so important to cybersecurity.

How Does DNS Scavenging Work?

The Domain Name System (DNS) is a critical part of the internet infrastructure, providing a way to map human-readable domain names to numerical IP addresses. DNS Scavenging is a process that helps keep the DNS clean and free of stale or outdated records.

When a DNS server receives a request for a domain name that it does not have in its records, it will send a query out to the internet root servers in an attempt to resolve the name. If the root servers are unable to resolve the name, the DNS server will then check for any cached records of recently resolved names that may contain the requested name.

If the requested name is not found in either the root servers or in the DNS server’s cache, then the DNS server will return an error message to the requesting client.

DNS Scavenging is a process that helps reduce these errors by periodically checking for and removing any stale records from both the root servers and from DNS caches. This helps ensure that users receive accurate information when they request it, and helps keep the internet running smoothly.

DNS Scavenging and DNS Aging

As I mentioned above, DNS scavenging and DNS aging usually work together to identify old DNS records. DNS Aging identifies the ‘stale DNS record’ from the DNS server by keeping track of its ‘age’, and to be more precise – its time stamps. The age of the DNS record is the difference between the last time stamp and the current time of the server. DNS scavenging uses this value to check if the record needs to be removed and after identifying the eligible stale resource records, proceeds in removing them from the DNS server.

Why Remove Stale DNS Records?

Stale DNS records can lead to problems within the DNS resolution (usually because they generate duplicate records), wasteful use of storage space, and reduced DNS server performance.

What Are the Benefits of DNS Scavenging?

One of the biggest benefits of DNS scavenging is that it can help to protect against distributed denial of service (DDoS) attacks. DDoS attacks are a type of attack where hackers attempt to overload a server with requests in order to cause it to crash. By scavenging DNS records, organizations can reduce the number of requests that their servers need to handle, making them less likely to be overloaded and more able to withstand an attack.

Secondly, it can help prevent DNS cache poisoning attacks. By removing stale DNS records from the cache, these attacks become much harder to carry out.

Finally, DNS scavenging can help improve internet speed. This is because when records are removed from the DNS system, it reduces the amount of data that needs to be transferred between servers. This can lead to a reduction in latency and an improvement in overall internet speed.

Enabling DNS Scavenging

DNS scavenging can be performed manually or automatically. Manual scavenging involves manually checking for and removing old DNS records. Automatic scavenging uses software to automatically find and remove old DNS records.

DNS scavenging can be enabled on a per-server or per-zone basis. The difference between zone scavenging and server scavenging is that zone scavenging only affects a single zone, while server scavenging affects an entire server.

To learn more about what how this feature works on a Windows Server and learn how to enable it, follow the steps in this article from Microsoft Community.

Potential Drawbacks of DNS Scavenging

DNS scavenging can cause problems if it removes records that are still in use. This can happen if a device is turned off for a period of time, or if there is a network issue that prevents the device from contacting the DNS server. When the device is turned back on or the network issue is resolved, the device will try to contact the DNS server to update its record, but will find that the record has been removed. This can cause errors and disruptions for users trying to access services on the affected device.

To avoid these problems, it’s important to ensure that devices are configured to update their DNS records regularly. This ensures that records are not removed prematurely, and that devices can quickly recover from any temporary network issues.

How Can Heimdal® Help?

If you want to further improve your company’s DNS security and really take it to the next level, Heimdal is your best bet! With the help of Threat Prevention – an advanced DNS security solution that combines cybercrime intelligence, Machine Learning, and AI-based prevention to predict and prevent potential threats with remarkable precision, you can secure both your endpoints and your network.

Whether on-site or remotely, Heimdal® Threat Prevention scans your users’ traffic in real-time, blocking infected domains and preventing communication with cybercriminal infrastructures. This gives administrators complete confidence while enabling unrestricted creativity and secure Internet browsing for all users.

Threat Prevention – Endpoint is based on the DarkLayer Guard engine, which is the world’s most advanced endpoint DNS threat-hunting tool. It also has our Threat to Process Correlation technology, which lets you find processes, users, URLs, and attacker origins that were used to get into your network.

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Wrapping Up

DNS Scavenging is an excellent practice in the cyber world, so it’s definitely worth giving it a try. After all, DNS aging and scavenging can help to protect against certain types of DNS attacks and can also help to keep the internet running smoothly. And if you want to further increase your company’s cybersecurity, you can always count on Heimdal to help you achieve it.

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