What is a DNS?

College students pursuing an informational technology degree need to study how the Internet works, and one of the most important systems of the Web is the Domain Name System. When it comes to connecting websites to people who are looking for information, products, and services online, DNS is the protocol that makes Web-surfing easy and practical. Instead of typing long sequences of letters and numbers into the address bar of a Web browser, people can type in the memorable name of a website, followed by a dot operator and suffix, such as “.com” or “.org” top level domain extensions. Understanding DNS is important for any information technology professional.

How Does DNS Work?

When a Web user types an address in a URL bar, a four-step process takes place before the browser can display the page in a window. The DNS recursor performs the first step of the process, receiving the lookup request from the user and translating it into a machine code that can be understood by other components in the DNS pipeline. The root server then converts the human-readable domain name into the IP address of a server. The root server works together with the TLD name server to narrow down the search further by focusing on a specific top level domain. The last step of the process is a request to the authoritative name server to return a link to the Web page associated with the domain, TLD and IP address. If the request is successful, the page loads in the user’s browser window.

What Is a DNS Resolver?

A DNS recursive resolver is a server near the beginning of the DNS pipeline. It initiates the DNS lookup request and notifies the authoritative name server by recursively searching for the server indicated in the request. This search is made more efficient by a process of caching that eliminates unnecessary lookups and saves the resolver from working harder than necessary. According to Cisco Umbrella, after contacting the name server, the recursive DNS resolver refers back to itself, like a telephone operator connecting a caller to a receiver. The authoritative name server is the link in the chain that contains the actual resource records of a Web domain. A Web page can’t load in a browser window until the authoritative name server is located by the resolver and the resource records are transferred back to the resolver. The process of looking up a Web page hosted on a subdomain requires sending a query to an additional authoritative name server after the initial name server has been located.

How Does DNS Look Up Names?

The recursive resolver performs several steps before it obtains the IP address of a Web server. It recursively contacts the root server, TLD server, and authoritative name server until it has the specific location of a Web page. After the resolver returns a website’s IP address to the browser, the HTTP request is sent to the correct IP address by the browser. When the request is answered, the browser can display the page in the window.

Information technology is a rapidly growing field that incorporates many aspects of modern technology and business in a professional discipline. The Domain Name System is one of the most important concepts to understand for college students pursuing an information technology degree.

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