What is DNS?
Domain Name System (DNS) is a name to IP address translation service, which is a distributed database implemented in a hierarchy of name servers. To facilitate the use of the internet DNS is invented. DNS is an application layer protocol that uses port 53 to communicate between client and server.
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In the early days of the internet, there were only a few computers, so it was easy to keep track of them all. As more computers joined the network, it became almost impossible to remember all the IP addresses. To solve this problem, Paul Mockapetris, a computer scientist, invented the DNS in 1983. This system made it much easier to manage the growing number of devices and websites on the internet.
There are several types of DNS servers, each with its own role in helping your computer find the right IP address for a website.
The main types are:
1. Root Name Server
2. TLD Name Server
3. Authoritative DNS Server
4. DNS Resolver (Recursive DNS Server)
2. TLD Name Server
3. Authoritative DNS Server
4. DNS Resolver (Recursive DNS Server)
DNS Resolver (Recursive DNS Server)
What It Does: Think of the DNS resolver as a detective. When you type a website name into your browser, the resolver starts investigating to find out the IP address of that website.
How It Works: When you enter a domain name, the resolver checks if it already knows the IP address from a cache (like its memory). If not, it starts asking other DNS servers to find the answer.
What It Does: The root name server is like the first stop on the detective's journey. It doesn’t have the exact answer but knows where to look next.
How It Works: The resolver asks the root name server where it can find information about the top-level domain (TLD) of the domain name, like .com, .org, or .net. The root name server then directs the resolver to the appropriate TLD name server.
TLD Name Server
What It Does: TLD name servers handle the top-level domains like .com, .org, and .net. They are like the sections of a library dedicated to different genres.
How It Works: After the resolver is directed here by the root name server, it asks the TLD name server where to find the authoritative name server for the specific domain (like google.com). The TLD name server then points the resolver to the authoritative name server.
What It Does: The authoritative DNS server is like the specific book on a shelf that has the information you need. It holds the actual records for the domain name.
How It Works: The resolver asks the authoritative DNS server for the IP address of the domain name. This server provides the final answer, and the resolver then returns this information to your browser.
Easy to Use: DNS makes it easy for us to use the internet without needing to remember complex IP addresses. We just type in the domain name, and DNS takes care of the rest.
Scalable: The DNS system can handle the enormous growth of the internet and the millions of domain names. It’s designed to expand as needed.
Redundancy: DNS servers are distributed all over the world. This means that even if some servers fail, the system as a whole keeps working, ensuring that websites remain accessible.
Load Distribution: DNS can distribute the load by directing users to different servers based on availability and geographic location. This improves performance and reliability, making sure that websites load quickly and efficiently.
Security Features: DNS supports security measures like DNSSEC (Domain Name System Security Extensions) to ensure that the data is authentic and hasn’t been tampered with.
While DNS is incredibly useful, it also has some security concerns. Here are a few common issues and how they can be mitigated:
What It Is: Attackers trick a DNS server into accepting false information, redirecting users to malicious sites.
Prevention: Implementing DNSSEC can help prevent this by ensuring that the data is authentic and has not been tampered with.
What It Is: Distributed Denial of Service (DDoS) attacks flood DNS servers with traffic, making them unable to respond to legitimate queries.
Prevention: Using anycast routing can distribute the traffic across multiple servers, reducing the impact of the attack.
What It Is: Attackers use DNS to bypass security measures and exfiltrate data from a network.
Prevention: Monitoring DNS traffic for unusual patterns and using security tools to detect and block tunneling activities.
What It Is: Attackers redirect queries to malicious DNS servers to steal information or spread malware.
Prevention: Using secure DNS services and regularly updating DNS configurations can help protect against hijacking.