What is DNS? Definition, Functions, Types, and How It Works

What is DNS?

The Domain Name System or DNS is a system that associates URLs with IP addresses. Why is DNS important? If there is no DNS, you have to type in the IP address to access a website.

It will be difficult for users to type the IP address since it contains numbers that are difficult to understand and memorize. For example, the IP address of Google.com is 172.217.0.142. With the DNS, you simply write the domain in the address bar.

The job of DNS is to translate the domain into an IP address that the computer understands so that you can access the website. So far, have you understood what DNS is?

Four Parts of DNS

URL and IP address have the same parts that explain each other. The role of DNS is to match the part of the URL with the IP address.

To get a deeper understanding about DNS, you need to know the four parts whose functions are interrelated with one another. The four parts of DNS are:

DNS Recursor

A DNS recursive resolver is a server whose job is to receive requests for IP address information from clients or users' computers through applications such as web browsers. The recursive resolver will search for information to provide answers based on client requests.

The search for information will start once the cache is stored in the browser. If it is not there, the Recursive resolver will continue to search the cache on the Internet Service Provider (ISP).

Root Server

The root server is a database that contains answers to questions about domain names and IP addresses. The job of the root server is to translate the domain name into an IP address. Not all questions can be answered by a root server. If the root server does not have an answer, then the request for information will be forwarded to the other party.

There are 13 root servers worldwide that are alphabetically ordered and managed by organizations, such as the Internet System Consortium, Verisign, the University of Maryland, and the U.S. Army Research Lab.

Top Level Domain (TLD) Server

Top Level Domain or TLD server is used to find a more specific IP address. For example, TLD .id for Indonesian servers, .org for non-profit organizations or institutions, and .sch for schools.

The information provided by the TLD will assist the system in forwarding the search for information to a server that has related data.

Authoritative Server

The authoritative server contains complete information about the website you want to go to. If the information sought is in accordance with the results, the browser will display the website to the user.

Some of the information on the authoritative server will be stored by the browser in the form of a cache. That way, the loading process will be faster when a user wants to re-access a website. Nevertheless, the browser will still continue to update the website information.

DNS Functions

To get a deeper understanding of what DNS is, then you also need to know its function. The explanation of the DNS functions are as follows:

• Identify the computer address in a network.
• Request IP address information based on the website domain.
• Request URL information of a website based on the IP address entered.
• Provide an IP address for each host.
• Find the appropriate data in the server database and display it to the client browser.
• List email servers and search for the right server to send email.
• Transcribing hostnames into IP addresses and vice versa.

Types of DNS

There are various types of DNS that you need to know. The explanations for each type of DNS are:

• A (Address) Record - Stores hostname, time to live, and IPv4 address information.
• AAAA or Quad A Record - Stores hostname information and its relationship to an IPv6 address.
• MX (Mail Exchange) Record - Records the SMTP server for sending email in a domain.
• CNAME Record - Redirects a domain or subdomain to an IP address.
• NS (Name Server) Record - Map a domain name into a single list of DNS servers for that domain.
• ANAME Record - Indicates the root domain to the hostname or FQDN.
• PTR (Pointer) Record - Redirects the IP address to a domain or hostname.
• SOA (Start of Authority) Record - Located at the beginning of the DNS zone and stores information about the domain the server is currently connected to.
• CERT Record - stores security certificates (encryption).
• TXT (Text) Record - Channels machine-readable data.
• SRV (Service) Record - Stores information related to DNS record specifications such as Priority, Name, Weight, Port, Points, and TTL.

How DNS Works

To give you a better understanding of what DNS is, you need to learn how it works. Here are the steps to understanding how DNS works:

1. The user types in the domain address. Requests for website information will be received by a DNS recursive resolver.
2. The recursor requests information to the root server. Then, the root server will assign the DNS TLD server address to the recursive resolver.
3. Afterward, the recursive resolver makes a request to the TLD server.
4. The TLD server provides a response in the form of a server IP address of the domain being searched for.
5. The recursive resolver sends the request to the domain nameservers.
6. Then, the IP address for the searched domain is returned to the recursive resolver.
7. The recursive resolver responds to the browser with the requested IP address.
8. After all the process is complete, the browser can send a request to the website to retrieve content with an existing IP address.