What is DNS Server?

Hello everyone, Welcome to my Blog!

Today we are going to learn about DNS (Domain Name System) Server and how it works. Let's get started without any further delay.

What is DNS?

DNS stands for Domain Name System. DNS is an application layer protocol, a naming system for computers that converts human-readable domain names e.g. (prabhathudda.com) into computer-readable IP addresses. DNS is something like a phonebook of the Internet.

In simple words, the DNS server resolves (translate) domain names into IP addresses.

A DNS server is just like a typical server, which contains the records and information of a domain with associated IP addresses. Once you search for a domain over the browsers, the DNS server fetches the data from its records for the searched domain and resolved it to the associated IP addresses.

Why DNS Server is required?

Humans access the Internet via domain names like prabhathudda.com, which can be remembered easily. However, web browsers and servers interact through IP addresses. Hence, DNS works by translating the domain into IP addresses to load the resources.

How DNS works?

Let's understand this via an example that you are looking for the website prabhathudda.com, hence following will be the steps:

1. You search for prabhathudda.com in your browser.
2. The browser will check its local cache for the prabhathudda.com information.
3. If the browser does not find the required IP address in its own cache, then it sends the query to the Resolver Server.
4. Resolver Server is nothing but your ISP (Internet Service Provider) such as Reliance Jio, will check its own cache (local cache) for the prabhathudda.com IP address. If the Resolver server does not find the required IP address in its own cache, then further it sends the query to the Root Server.
5. Root Server is the top level of the DNS with 13 sets operated by 12 different organizations across the globe, redirect the resolver server to the TLD (Top Level Domain) server for the top level domain.
6. TLD server checks the top-level domain information such as .com, .net, .org, etc of the requested domain and redirects the resolver server to the Authoritative Server.
7. The authoritative server knows about the IP address of each domain. The authoritative server fetches the information and sends the information to the resolver server.
8. The resolver server stores the information in its local cache and sends the information to the Web browser.
9. The browser stores the information in its local cache and searches the resource with its IP address.
10. The resource server will be located with an IP address and serve the resources to the client.

Now, let's try to understand something more about DNS.

What is DNS RR?

DNS RR (Resource Record) is the unit of information entry in DNS zone files. RER (Resource Record) is the basic building block of host-name & IP information, which are used to resolve all DNS queries.

Types of DNS records (common):

• A record: Maps a hostname to a 32-bit IP address. The record holds the IPv4 addresses of a domain.
• AAAA record: Maps a hostname to a 128-bit IP address. The record holds the IPv6 address of a domain.
• CNAME record: Forwards one domain or subdomain to another domain, does not provide an IP address.
• MX record: Mail exchange record. This basically tells us which server is responsible for receiving mail sent to that domain name.
• NS record: Stores the name server for the DNS entry. Delegates a given zone to use the given authoritative nameserver. For e.g. ns1.google.com is an authoritative nameserver for google.com.
• TXT record: Let an admin store text notes in the record.
• SOA record: Stores admin information about a domain.
• SRV record: Specifies a port for specific services.
• PTR record: Provides a domain name in reverse lookups. A pointer-most common use for implementing reverse DNS lookup.

Thank You!