DNS is one of the systems that many people have difficulty understanding. DNS allows websites to be found easily without any problems. It allows you to easily connect to millions of websites around the world. Domain Name System, “DNS” is used to name segments on the Internet and coordinate communication between segments. It is used as a distributed naming system for a resource connected to a computer, the Internet, or a private network. The device name and the Internet “domain” are referred to as Host. Thanks to DNS, the IPs of all devices running on computers or computer systems are resolved and they are able to communicate with each other.
What is DNS?
All units that make up the Internet network have an IP address of their own. These IP addresses turn into easy-to-remember addresses such as www.site_domain.com for the convenience of users. DNS servers keep the IP addresses of internet addresses registered.
The domain names assigned to each of the users contain various information. It basically converts domain names, which can be memorized by users in a practical way, into numeric IP addresses to suit computer services and devices around the world. DNS is an essential component for the functionality of many internet services because it is the primary administrative service.
Back in the 1970s, ArpaNet was quite small compared to today’s networks. It served only a few hundred systems. At that time, naming was done by finding a file located in a single location. The remaining systems periodically updated this file on their own side, which solved the naming problem at that time.
With ArpaNet, the HOST.TXT file developed on a computer acting as a DNS server kept records of IP address and domain name mappings. Thus, name resolutions were configured. This is how the TCP/IP system started using the DNS system for name resolution. Today, we still have HOST.TXT files on our computers. You can also register your IP address and domain name yourself.
The History of DNS
DNS has been around since 1984. Before 1884, similar operations were performed with a text file called “HOSTS”. As the number of computers increased over time, the computer files stored on “HOSTS” became very large. One of the biggest cons of this system was that each computer was given a different name. It was impossible to keep the system constantly updated. This is why that system had to change.
DNS was developed to solve these problems. DNS complicated tHow does DNS work?
Computers and browsers have a recording system called Cache. The IP address of a website you visit once and some content information about the site are saved in memory. This information can be quickly retrieved from memory when asked again. Thus, you do not need to query the entire DNS system again. However, when you are trying to find a domain name that you are visiting for the first time, here is how DNS works, using the information we have provided about DNS and its components.
How does DNS work?
Computers and browsers have a recording system called Cache. The IP address of a website you visit once is saved in memory along with some content information about the site. This information can be quickly retrieved from memory when desired. Thus, you do not need to query the entire DNS system again. However, using the information we have provided about DNS and its components, this is how DNS works when you are trying to find a domain name that you are visiting for the first time.
Step 1: When you type a domain name in the browser, you make an IP address query to the Internet Service Provider. The DNS resolver reaches the Root Server to which it is connected to and queries the IP address of the domain name.
Step 2: In order to find the IP address of the queried domain name, the Root Server redirects you to the TLD Server for the extension it is connected to.
Step 3: The TLD Server finds the Name Server where the name is stored in accordance with its extension and redirects you to the authorized Name Server.
Step 4: In the last step, the authorized Name Server provides the IP address information of the domain name it hosts within the Name Server. The browser uses this IP address information to allow you to establish a direct connection with the server to which the website is connected.
Why Do We Change DNS?
In some cases, you may not be able to access all the sites on the internet with your current DNS settings. In such a case, you may want to change the DNS. You can use DNS registries to perform this change process. In addition, DNS change processes for Android, Windows and IOS applications act differently. With these processes, you can change the DNS of your computer or phone in a practical way. Another reason for changing DNS can be to increase speed and security. Thus, you can use a much faster and more secure internet connection. Another situation is to prevent unwanted content, you can block adult content with DNS records. Sometimes BTK (Information and Communication Technologies Authority) in Turkey, blocks some websites via DNS as a result of court decision.
What are the Files Required for DNS?
There are different types of files used for DNS. You cannot run DNS without certain file types. We can list these file types as follows.
boot: This file type is the first file to be read when DNS starts up.
local: This file type is used to effectively resolve the address that the machine points to.
ca: This file type is known as “named.ca” and contains the addresses known as the root server.
hosts: This file type is known as “named.host” and contains the addresses of all machines moving in the DNS.
reverse: The “named.reverse” file is used to convert the IP addresses in the “named.hosts” file into the name of the machine.
What is DNS Caching and Where Does It Take Place?
The record of DNS resolution operations is kept in the cache. This eliminates the need to make a new query every single time. When a DNS resolution operation is performed and the domain name and IP address match, this resolution information is first saved in the Cache of the DNS server. These records have a storing time called TTL (Time To Live). When the time runs out, the query is repeated and if there are changes, it is saved as Cache again. The DNS resolution information sent to the browser is also saved in the browser cache. Thus, there is no need to requery at different times according to the Cache reservation periods.
