What is DNS? How to Change DNS Settings?

DNS (Domain Name System) is a system that maps the IP addresses of computers and other devices on the Internet to more understandable and easy-to-remember domain names. This system allows people to access sites or other Internet services they visit through their web browsers without having to know their IP addresses.

The basic tasks of DNS are as follows:

Domain Name Resolution:

When users type the name of a website (for example, www.example.com) into their browsers, DNS resolves the domain name to the relevant IP address and meets the user’s request. This process allows users to browse the Internet using understandable domain names.

Provision of IP Address Records:

DNS contains a series of records to map domain names to IP addresses. For example, the “A” record (Address Record) maps a domain name to an IPv4 address, while the “AAAA” record (IPv6 Address Record) maps it to an IPv6 address.

Domain Name Hierarchy:

DNS has a hierarchical structure. At the top, there are root DNS servers, which direct to lower-level DNS servers. In this way, when resolving a domain name, queries start from the root servers and proceed to lower-level servers.

Acceleration and Storage (Caching):

DNS speeds up repeated queries by storing frequently used IP address solutions in memory for a while. This allows queries to the same domain names to be performed more quickly.

DNS Security (DNSSEC):

DNS includes security measures such as DNSSEC (DNS Security Extensions) to protect against security threats. DNSSEC ensures the integrity and accuracy of DNS responses, so that users are directed to the correct IP address.

DNS is one of the basic infrastructures of the internet and makes browsing the internet more user-friendly for users. It also plays a critical role in computer-to-computer communication and the operation of internet-based services.

DNS Working Principle

DNS (Domain Name System) is a system that matches the IP addresses of computers and devices on the internet with domain names. The working principle of DNS comes into play when a user enters a domain name into their browser, and this process consists of the following steps:

Namespace Query:

When a user wants to access a website, the browser requests that this domain name be resolved by querying DNS. For example, if the user wants to visit “www.example.com”, a query is made to DNS.

Cache Check:

DNS stores previously resolved domain names and IP addresses in its memory for a while. First, the browser checks this solution in its cache. If this solution is in the cache, the user is directed directly to the desired site without the need for a repeat query.

Regional DNS Server Query:

If the solution is not in the cache, the browser queries the local DNS server (provided by the ISP). This server is usually determined based on the user’s geographic location.

Root DNS Server Query:

If the local DNS server cannot find the solution, the root DNS servers are directed. Root DNS servers contain the addresses of all domain name extensions (top-level domains – TLDs) and the top-level DNS servers belonging to these extensions (authoritative DNS servers).

Top-Level Domain (TLD) Server Query:

With the information received from the root DNS servers, the local DNS server queries the TLD servers. TLD servers are the servers that manage the extensions at the end of the domain name (such as com, net, org).

Authoritative DNS Server Query:

With the information received from the TLD server, the local DNS server queries the authoritative DNS server, which contains the entire domain name. The authoritative DNS server contains the IP address that matches a specific domain name.

IP Address Response:

With the IP address information received from the authoritative DNS server, the local DNS server forwards this information to the browser and directs the user’s computer to the correct IP address.

Browser Redirection:

By redirecting to the received IP address, the browser allows the user to reach the desired website.

How to Change DNS Settings?

Changing DNS settings is usually a method of connecting to the internet on a computer, smartphone, or other device. Here are the general steps to change DNS settings on different devices:

Windows Operating System:

Opening Network Connections:

Go to Control Panel and open “Network and Sharing Center.” Then, open the network connections window by clicking the “Change adapter settings” link.

Selecting the Network Connection:

Right-click on the network connection you are using and select “Properties.”

Changing Internet Protocol Version 4 (TCP/IPv4) Settings:

Select “Internet Protocol Version 4 (TCP/IPv4)” and then click “Properties.” From there, check the “Use the following DNS server addresses” option and enter your DNS addresses.

macOS Operating System:

Opening System Preferences:

Open Network Settings:

Click the “Network” icon and then select the network connection you are connected to.

Change DNS Settings:

Click the “Advanced” button and then select the “DNS” tab. From here, you can add new DNS addresses or edit existing ones by clicking the “+” button.

Android Devices:

Open the Settings Menu:

Open the Settings app.

Enter Network & Internet Settings:

Go to “Connections” or “Network & Internet”.

Change Wi-Fi Settings:

Select the Wi-Fi network you are connected to and go to advanced options such as “Advanced” or “Network Settings”.

Change DNS Settings:

Find “IP Settings” or “DNS” and enter your custom DNS addresses.

iOS Devices:

Open the Settings App:

Open the Settings app.

Open Wi-Fi Settings:

Go to “Wi-Fi” and select the network you are connected to.

Change DNS Settings:

Change “DHCP” to “Static” and then enter your custom DNS addresses in the “DNS” field.

Router (Modem) Settings:

Log in to the Management Interface with a Browser:

Open your browser and type your modem’s IP address (usually 192.168.1.1 or 192.168.0.1) into the address bar to log in to the management interface.

Login Information:

Enter your username and password to log in to the management interface. You can find this information in your modem’s documentation or on the bottom of the device.

Change DNS Settings:

In the management interface, usually go to the “DNS” or “Internet” tab. You can enter your custom DNS addresses from here.

Changing DNS settings can often be used to provide a faster and more reliable internet experience or to bypass restrictions on accessing content. However, you should be careful when changing these settings and prefer reliable DNS services.

DNS Security and Threats

DNS Spoofing:

A type of attack in which attackers try to mislead users by replacing DNS responses with fake information. Such attacks can direct users to false websites and expose them to malicious content.

DNS Amplification Attacks:

Attackers usually try to amplify attacks on a target system by generating large amounts of DNS traffic. Such attacks are usually carried out using open DNS servers.

Cache Poisoning:

An attack in which an attacker adds false information to the cache of DNS servers. This can cause the misleading information to be stored in memory for a period of time, causing users to be presented with false IP addresses.

DNS Tunneling:

DNS tunneling is a technique in which malicious software developers gain control and data transfer using the DNS protocol. Such attacks can be used to bypass firewalls and hide network traffic.

Pharming:

A type of attack that involves attackers changing DNS records to deceive users. When users try to go to a real website, they are redirected to a fake site controlled by the attackers.

DNSSEC Deficiency:

DNS Security Extensions (DNSSEC) is a security mechanism to address security vulnerabilities in DNS. However, many DNS servers still do not implement DNSSEC, creating an environment open to potentially malicious attacks.

How is DNS Security Provided?

Using DNSSEC:

DNSSEC is a security protocol that adds a layer of security to DNS. Using DNSSEC, the integrity and correctness of DNS queries can be ensured.

Trusted DNS Servers:

Using trusted DNS service providers can provide a more secure DNS experience. For example, Google DNS (8.8.8.8, 8.8.4.4) or OpenDNS.

DNS Firewalls:

DNS firewalls can increase network security by blocking malicious DNS queries. These types of walls protect against known malicious sites and DNS sources.

Up-to-date DNS Server Software:

It is important to have up-to-date and security-patched DNS server software. Fixing vulnerabilities can increase resistance to potential attacks.

Reviewing DNS Settings:

It is important to regularly review DNS settings on personal devices or network infrastructure and use secure DNS providers.

DNS security is a critical element for protecting the security of Internet users and organizations. Reliable DNS service providers and security measures can provide more effective protection against DNS-based attacks.

DNS Hierarchy and Resource Records

DNS Hierarchy:

DNS has a hierarchical structure, which allows a specific order to be followed when resolving a domain name. This hierarchy is as follows:

Root Domain:

The highest level, the domain name level at the top of the hierarchy. It is represented as a “.” (dot). The root domain redirects to TLD (Top-Level Domain) names.

Top-Level Domain (TLD): After the root domain