What Is a DNS Server

The Domain Name System (DNS) Server is a computer that matches website hostnames (such as example.com) to their corresponding Internet Protocol (IP) addresses. A database of public IP addresses and their matching domain names is kept on the DNS server.

According to the IPv4 or IPV6 protocols, every device connected to the internet has a unique IP address that helps to identify it. The same may be said for web servers, which are used to host websites. One CDNetworks server in Mountain View, California, for example, has an IP address of 157.185.170.144.

DNS servers assist us to avoid memorizing long IP addresses (and even more complex alphanumeric ones in the IPV6 system) by automatically translating website names into these numbers so that the servers can load the correct web pages.

What Is DNS?

The Domain Name System (DNS) is a database of domain names and IP addresses that allows browsers to locate the correct IP address for a hostname URL. When we want to access a website, we usually type the domain name into the web browser, such as cdnetworks.com, wired.com, or nytimes.com.

DNS Server

However, in order to load content for a website, web browsers need to know the specific IP addresses. The Domain Name System (DNS) converts domain names to IP addresses, allowing resources to be loaded from the website’s server.Websites with multiple IP addresses belonging to a single domain name are not uncommon.

Large sites like Google, for example, will have users requesting a server from all over the world. Even if the site name entered in the browser is the same, the server that a computer from Singapore tries to connect will most likely be different from the one that a computer from, say, Toronto tries to reach. This is when DNS caching enters the picture.

DNS Caching

DNS caching is the technique of storing DNS data on DNS records that are closer to a requesting client so that the DNS query can be resolved faster. This eliminates the need for extra requests farther down the chain, improves web page load times, and lowers bandwidth usage.

Time to live, or TTL, refers to how long DNS records are retained in the DNS cache. This time frame is significant since it defines how “fresh” DNS records are and whether they match current IP address revisions.DNS caching can take place in the browser or on the operating system level (OS level).

DNS Caching In The Browser

Because web browsers save DNS records for a set period of time, it’s frequently the first place a user looks when creating a DNS record. There are fewer steps involved in verifying the DNS cache and making a DNS request to an IP address when using a browser.

DNS Caching The Operating System (OS) Level

When a DNS query leaves an end user’s workstation, it goes to the operating system level to look for a match. The “stub resolver” process in the operating system checks its own DNS cache to determine if it has the record. If not, the query is directed to the Internet Service Provider outside of the local network (ISP).

How Does a DNS Work?

The DNS is in charge of transforming the hostname (also known as the website or web page name) to an IP address. The process of locating the corresponding IP address is known as DNS resolution, and the act of inputting the domain name is known as a DNS query.

There are three types of DNS queries: recursive, iterative, and non-recursive.

Recursive queries are those in which a DNS server is required to respond with the resource record requested. If a record cannot be discovered, an error message must be displayed to the DNS client.

Iterative inquiries are those in which the DNS client requests responses from numerous DNS servers until the best response is discovered, or until an error or timeout occurs. If a DNS server authoritative for a lower level of the domain namespace is unable to locate a match for the query, it will refer to a DNS server authoritative for a lower level of the domain namespace. The DNS client then queries this referral address, and the process repeats with more DNS servers.

Non-recursive queries are those that a DNS resolver resolves when the requested resource is available, either because the server is authoritative or because the resource is already cached.

The Different Types of DNS Server

A DNS query is sent to a few distinct servers before being resolved, with no involvement from the end-user.

1. DNS Recursive Resolver

This is a server that is dedicated to receiving requests from client machines. It locates the DNS record and performs additional requests in response to the client’s DNS queries. When the requested resources are returned to the recursor early in the query process, DNS caching can reduce the number of queries.

2. Root Name Server

This server is in charge of converting human-readable hostnames into computer-readable IP addresses. The root server accepts the recursor’s query and, based on the domain name in the query, transmits it to the TLD nameservers in the next stage.

3. Top-Level Domain (TLD) Nameserver

The TLD nameservers are in charge of keeping track of domain name information. They could, for example, include information about websites ending in “.com” or “.org,” as well as country-level domains such as “www.example.com.uk,” “www.example.com.us,” and others. The TLD nameserver receives the query from the root server and forwards it to the authoritative DNS nameserver for the domain in question.

4. Authoritative Nameserver

The authoritative DNS nameserver will finally return the IP address to the DNS recursor, which can then relay it to the client. This authoritative DNS nameserver is the one that keeps the DNS records at the bottom of the lookup process. Consider them your last stop or the ultimate authoritative source of information.

Conclusion

A DNS lookup is the procedure through which a DNS server returns a DNS record. It entails passing the hostname query from the web browser to the DNS lookup process on the DNS server and back. The DNS resolver is the server that handles the first stage in the DNS lookup process, initiating a series of procedures that culminate in the URL being translated into an IP address for web page loading.

The DNS recursive resolver receives the user-entered hostname query after it travels from the web browser to the internet. The recursive DNS server then sends a query to the DNS root server, which returns the address of the TLD server responsible for domain storage.

The resolver then sends a DNS request to the associated domain’s TLD, receiving the domain nameserver’s IP address. The recursive DNS server next requests the domain nameserver and receives the IP address to give to the web browser as the last step. The browser can then use HTTP requests to request particular web pages after the DNS lookup process is completed.

These phases make up a conventional DNS lookup procedure, however DNS caching can speed things up. DNS caching allows the browser, operating system, or a distant DNS infrastructure to store DNS lookup information locally, allowing some steps to be skipped for faster loading.

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