What is DNS? Introduction to DNS Security and How It Works


What is Domain Name System (DNS)? How DNS works? The URL you type into the search bar and the IP address your system reads aren’t the same. URLs are human-readable, whereas machines require IP addresses, made up of numbers and letters, to fulfill a query. This is where DNS comes in, and it is essential to establish a connection between you and your requested site. DNS security, therefore, is essential to establish a secure connection. The 2022 Global DNS Threat Report found over 88% of surveyed companies had experienced DNS attacks, suffering system downtime as a result. Understanding how DNS works and why its security implementation is necessary can help keep your systems safe from attacks.

Importance of DNS Security

Domain Name System (DNS) queries match URLs to their respective IP address, which is unique for each site, to connect users to their intended site. In the same way, frequently visited URLs- and the corresponding IP address- are often cached so they can be accessed quickly every time.

DNS protocols have existed since the advent of the internet, and are therefore used in all facets of the online world. For this reason, they are subject to excessive and frequent attacks and also require something more sophisticated than a simple firewall for protection. DNS security can be a little difficult to implement by traditional methods, as the purpose of the protocol is to allow the user access to information. Traditional techniques use blocking methods, which are ineffective at best.

To implement effective DNS security, you need to know what type of threats you are trying to prevent.


Types of DNS attacks

DNS security is an essential aspect of establishing a secure connection between users and their intended websites. DNS attacks are prevalent, with over 88% of surveyed companies experiencing them. It’s crucial to comprehend the various types of threats that DNS servers face, such as cache poisoning, DNS hijacking, and DDoS attacks. DNS security can be ensured by adopting a multi-layered approach that involves investing in infrastructure, implementing DNS resolvers, firewalls, and DNSSEC, among other measures. By adopting such a comprehensive approach, internet providers like Spectrum can protect against the potential DNS attacks.

There are two main types of DNS services, which can be subjected to attacks. These include:

Recursive attacks

Recursive DNS service acts as the middleman to user requests. It does not hold any DNS records itself, but rather passes them on to authoritative servers to fulfill the query. Recursive DNS servers do hold cached information, so if the query is in regards to a cached URL, it can provide users with the related IP address. Recursive attacks include:

  • Cache Poisoning attacks: Invalid information is placed in a DNS cache, which is assumed to be valid when used. This information diverts traffic from a valid query to an unsafe server.
  • DNS hijacking: valid queries are altered to lead users to malicious sites.

Authoritative attacks

Authoritative DNS servers deliver the response to user queries, after receiving them from a recursive DNS server.  It manages public DNS names and is responsible for translating URL requests into IP addresses. Authoritative DNS servers are called so for the final authority they exert in accessing sites. Authoritative attacks include:

  • DDoS attacks: A distributed denial of service (DDoS) attack is used to overwhelm destination sites with fake, bot-generated traffic. This then makes the site unavailable to actual users.
  • Amplification attacks: A form of DDoS attack where a high volume of packets are generated to overwhelm a site, using the first “trigger packet” that an attacker receives in response to their request
  • Reflection attacks: Queries are made from a spoofed IP address, which the server responds to on the target’s IP address. These magnify the traffic generated while covering the source of the attack.

These are just a few examples of the types of attacks DNS servers are vulnerable to. They can leave your system at risk without the proper DNS security protocols.


Establishing DNS Security

There are a few steps you can take to limit the threat of DNS attacks. These include:

DNS Security Extensions (DNSSEC)

DNSSEC digitally ensures the validity of data to ensure its transmission is secure at every level. This security protocol signs the data and queries at every stage of lookup to maintain security. The unique signature implemented by DNSSEC cannot be replicated, and so ensures the data is valid, original, and has not been tampered with.

This protocol is not meant for independent use but should be combined with other security protocols for an effective strategy. DNSSEC provides data authentication at every level, creating a chain of trust that cannot be compromised. Any vulnerability along this chain threatens the entire query.

DNS infrastructure

IT administrators may look into investing in infrastructure as a defense strategy against DNS attacks. Greater server space, for example, can help manage much higher volumes of traffic that you expect to receive. This can make volume-based attacks, like an amplification attack, ineffective, as servers will not be overwhelmed by the sudden onslaught of traffic.

DNS resolvers

DNS resolvers can use a variety of security-based solutions to protect against DNS attacks. This includes content filtering, which can block access to known malicious sites, or those suspected to be the source of spam and malware. Botnet protection can help identify and block communication with botnets, preventing DDoS attacks.

A DNS firewall may also be an effective security strategy. It acts as a buffer between the user’s recursive DNS server and the target site’s authoritative server. It is then able to prevent attacks and keep the site running from cached information.


DNS Security is Essential

Given the widespread reliance on DNS, especially with the increasing use of cloud computing, DNS security protocols are a necessary part of any organization’s security infrastructure. Understanding the threats posed by vulnerabilities in DNS servers is the first step to countering them effectively. Given the nature of DNS servers and their function, no single security approach is effective on its own. A holistic approach using multiple security protocols is needed for definite safety.


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