Introduction
DNS is an essential element of the Internet’s infrastructure. It translates the IP address into human-readable domain names, allowing users to access websites or other online services.
If there is no DNS, the users must remember the IP address to access the website, which is impossible.
For example, the IP address for google.com is 172.253.116.190; here, google.com is easier to remember than 172.253.116.190.
What is the Domain Name System?
DNS stands for Domain Name System. It is a decentralized and hierarchical naming system that connects/translates domain names to IP addresses.
A domain name is associated with one or more IP addresses. In contrast, each IP address serves as a unique identifier for a device on the Internet. Upon entering a domain name into a web browser, the browser requests a DNS resolver.
The DNS resolver then searches for the IP address linked to the domain name within a hierarchical network of DNS servers. After the resolver obtains the IP address, it returns the information to the browser.
Subsequently, the browser connects with the server hosting the website or online service.
Types of DNS Records
DNS records keep track of domain names and the IP numbers that go with them. There are different kinds of DNS records, and each one is used for another thing:
- A (Address) Record: The A record is the most basic DNS record type. It connects a domain name to the IP address that goes with it. It points a name or subdomain to a specific IP address.
- CNAME (Canonical Name) Record: A CNAME record gives a domain an alias or short name. It lets you connect multiple domain names to the same IP address. For example, you can make a CNAME record for “www” and map it to the domain name to make it easier for people to remember.
- MX (Mail Exchange) Record: The MX record tells the world which mail server is in charge of receiving email for a name. It lets you set up email services for a name and ensure messages go to the correct server.
- TXT (Text) Record: A DNS record’s TXT record stores any kind of text data. It can tell people more about a domain or prove that someone owns a name.
- NS (Name Server) Record: The NS record is used to say which name servers are the most important for a site. It tells other DNS servers where to look for information about a name.
- SRV (Service) Record: The SRV record details services on a domain, like where a particular service is located.
The company that registers domain names or hosts DNS oversees DNS records. They can be changed or updated as needed to keep up with domain name or IP address changes.
How DNS Resolves Names?
The process of turning domain names into IP addresses is called DNS resolution. DNS is in charge of converting domain names that people can understand to IP numbers that computers can understand. Users can visit websites, send emails, and do many other things on the Internet without knowing their IP addresses. Name discovery in DNS takes several steps, which will be explained in this piece.
Step 1: Lookup in the local DNS cache
When a user types a domain name into a web browser, the browser first looks for the IP address in the local DNS cache on the user’s computer. The DNS cache keeps track of the DNS information that has been used most recently. This helps speed up the process of resolving DNS names. Suppose the cache already has the IP address for the domain name. DNS resolution is done in that case, and the computer can connect to the website.
Step 2: Lookup on multiple DNS servers
Suppose the domain name is not in the local DNS cache. In that case, the browser requests the recursive DNS server set in the computer’s network settings. A recursive DNS server asks other DNS servers on behalf of the client for information until it gets the information it needs.
The recursive DNS server asks the root name servers which official name servers are in charge of the desired domain name’s top-level domain (TLD). If the domain name you want is www.example.com, for example, the TLD is .com.
Step 3: TLD Name Server Lookup
The recursive DNS server then asks the TLD name servers which official name servers are in charge of the second-level domain of the domain name that was asked. In our case, the TLD name servers would return the official name servers for the example.com domain.
Step 4: Look up the correct name server
The official name servers are then asked for the IP address of the desired domain name by the recursive DNS server. The DNS records for a given domain name are stored on the official name servers.
If the official name server has the DNS record that was asked for, it gives the recursive DNS server the IP address. The recursive DNS server saves the IP address in its cache and sends it back to the user’s web browser.
Step 5: Give a reply to the user
Once the web browser has the IP address for the domain name, it can connect to the web server that the IP address points to. The web server then sends back the page that was asked for, and the person can look at it in their web browser.
Common DNS Issues
DNS can have problems that can cause trouble for people who use the Internet.
- DNS Server Unavailable
When the DNS server goes down, it’s one of the most common problems with DNS. This can happen for several reasons, such as a computer being too busy, a server repair, or network problems. If this happens, you won’t be able to go to any website by typing in its domain name.
To fix this problem, try turning on your router or modem again. If the problem continues, talk to your internet service provider (ISP) to see if their DNS servers are having trouble.
- Poisoning the DNS cache
DNS cache poisoning is a type of attack in which an attacker sends fake information to a DNS server, making it store the false information. This can lead to users being sent to fake websites or sites that try to steal information.
To fix this problem, you should regularly clear your DNS cache. You can do this by typing “ipconfig /flushdns” on Windows or “sudo kill all -HUP mDNSResponder” on Mac.
- DNS Hijacking
DNS hijacking is an attack in which an attacker changes a computer’s or server’s DNS settings to send people to fake websites or phishing sites.
Check your DNS settings to ensure they are set to the correct numbers. This will fix the problem. You can also use a DNS service like DNSSEC or DNS-over-HTTPS (DoH) that offers DNS protection.
- DNS Propagation Delay
When changes to DNS records take longer to spread across the Internet, this is called a “DNS propagation delay.” This can lead to users being sent to the wrong website or waiting longer for pages to load.
To fix this problem, you can wait for the delay to go away. This can take anywhere from 24 to 48 hours. You can also cause the DNS record to update by clearing your DNS cache.
- DNS Server Not Set Up Right
When the DNS server is not set up correctly, this can lead to DNS server misconfiguration. This can cause DNS searches to fail or give the wrong information.
To fix this problem, check how your DNS service is set up and ensure it is set up correctly. You can also restart or restore your DNS service to its regular settings.
DNS Security
DNS is now a target for many cyber dangers, making DNS security an essential part of network security.
- DNS Spoofing and Cache Poisoning
DNS faking, also called DNS cache poisoning, is a way for attackers to send traffic from a genuine website to a fake one. This lets them steal private information or put malware on the victim’s computer.
The attacker changes the DNS records in the victim’s computer’s cache or on a DNS server. This causes traffic to be sent to the attacker’s evil website. To stop DNS fraud, it is essential to ensure the DNS server is accurate and to use DNSSEC, which adds digital signatures to DNS records to ensure they are real.
- DNS Amplification and Reflection Attacks
DNS amplification and reflection attacks are two types of DDoS attacks that take advantage of weaknesses in the DNS system. In DNS amplification attacks, the attacker sends many DNS queries to open DNS servers. The open DNS servers reply with extensive DNS responses, which send more data to the victim’s system.
DNS reflection attacks work similarly but use fake IP addresses to send big DNS replies to the target system. DNS servers must be set up to stop these attacks so they can’t be used in DDoS attacks, and traffic-blocking methods must be used to find and prevent malicious traffic.
- DNS Tunnelling
DNS tunneling is a way for attackers to get around firewalls and other security measures by sending illegal data through DNS requests and replies. Attackers use this method to move private data out of a secure network or get to usually locked down resources. To stop DNS tunneling, it’s essential to keep an eye on DNS data and use DNS security tools to find and destroy illegal DNS requests.
- Malware based on DNS
DNS-based malware attacks are a type of malware that communicates with the attacker’s command and control services by sending and receiving DNS requests and replies. The malware sends DNS queries to the command and control server to get orders. It sends DNS replies to the attacker’s system to send data. To stop DNS-based malware attacks, you must use tools to find malware and monitor DNS data for any strange behavior.
Conclusion
DNS is an integral part of the Internet that lets people access websites and other online services by turning domain names into IP addresses. It is a structured, decentralized system with many parts, such as resolvers, root servers, TLD servers, and official DNS servers.
DNS records store information about domain names and the IP addresses that go with them. Several security steps have been taken to keep DNS breaches from happening. No matter how often you use the Internet or how well you know it, you must understand how DNS works.
