Understanding DNS: How It Works and How Hackers Take Advantage of It

What is DNS?

DNS stands for Domain Name System. It’s what helps translate human-friendly domain names into machine-friendly IP addresses. For example, when you type example.com into your browser, your system doesn’t magically know where to go. Instead, it uses DNS to figure out the actual IP address behind that domain name so that it can communicate with the right server.

How DNS Works

Let’s break it down. When you type a website address like example.com into your browser, the browser can’t connect straight to the website just yet. It needs to know the IP address first. That’s where the DNS Resolution Process kicks in.

Think of it like a giant library. You’re looking for a book, but you don’t know which shelf it’s on. So, you go to the librarian and ask. The DNS system works in a similar way. Your browser sends a DNS query—asking, “Where can I find example.com?”

The first place it checks is called the Root Server. This server doesn’t have the exact IP address, but it knows where to look next. It gives directions to a TLD (Top-Level Domain) Nameserver—like the specific shelf in the library that holds ".com" websites.

That TLD Nameserver then points your query to the Authoritative Nameserver, which is like the dictionary on the shelf. This one actually contains the IP address of example.com. Once it finds it, the IP address is sent back to your browser, and only then does the connection to the website begin.

DNS Vulnerabilities

Even though DNS is super useful, it’s not bulletproof. It has some weak spots that hackers love to target. One common issue is that traditional DNS doesn’t have strong encryption. This means attackers can spy on your DNS requests or even change the responses you get. This is called DNS spoofing or cache poisoning.

Another problem is with open DNS resolvers. These are servers that answer DNS queries from anyone on the internet, not just their own users. Hackers can use these to launch DDoS amplification attacks, sending a tiny request and causing a huge response to be sent to a target, overwhelming their network.

How Hackers Exploit DNS

So how do hackers actually take advantage of these DNS weaknesses? There are a few ways:

• DNS Spoofing: Attackers insert false information into the DNS cache. So when you think you’re visiting your bank’s website, you’re actually being sent to a fake one that looks identical.
• DNS Hijacking: Hackers change DNS settings on your router or device so that all your traffic goes through malicious DNS servers. From there, they can monitor or manipulate everything you do online.
• Data Exfiltration via DNS: Some attackers hide stolen data inside DNS queries, slowly leaking it out without triggering security alarms.
• DDoS Amplification: By sending small spoofed requests to open DNS resolvers, hackers can flood a victim with large volumes of data, taking down their services.

That’s why securing DNS is a big deal. If left open or unmonitored, it can be a huge weak spot in your network. Using DNSSEC, encrypted DNS (like DoH or DoT), and properly configuring your resolvers can help lock things down.