DNS in Computer Network

All computers on the Internet, from your smartphone or laptop to the servers that serve content for large retail websites, use numbers to find and communicate with one another. These numbers are referred to as IP addresses. You don’t have to remember and enter a long number when you open a web browser and go to a website. Instead, you can enter a domain name such as example.com and still be directed to the correct page. The global nature of Internet services requires a network of distributed and scalable DNS servers to ensure that users can quickly look up and resolve the requested server’s location, no matter where they are in the globe. DNS’s purpose is to convert a domain name into an IP address. In this article we will discuss domain name systems in computer networks, DNS caching, the working of Domain Name Systems in computer networks, and types of DNS servers.

What is DNS in a Computer Network?

The Domain Name System in computer networks is essentially the internet’s phonebook. The DNS matches a website name to its corresponding IP address in the same sense that a phonebook matches people to phone numbers.DNS is a hostname for IP address translation service. DNS is a distributed database implemented in a hierarchy of name servers. It is an application layer protocol for message exchange between clients and servers.

Websites may have several IP addresses corresponding to a single domain name. Large sites, like Google, will have users querying a server across the world. Even if the site name entered in the browser is the same, the server that a computer in Singapore tries to query will most likely be different from the one that a computer in Toronto tries to reach. DNS caching plays a role here.

The domain name space is divided into three different sections:

1) Generic Domains
Generic domain: .com(commercial) .edu(educational) .mil(military) .org(nonprofit organization) .net(similar to commercial) all these are generic domains. It categorizes the registered hosts based on their general behavior. The domain name, which is an index to the DNS database, is defined by each node in a tree.

2) Country Domain
Country domains have the same format as generic domains, but they use two-character country abbreviations (e.g., us for the United States) instead of three-character organizational abbreviations. for ex Country domain .in (India)

3) Inverse Domains
The inverse domain is used to map an address to a name. When the server receives a request from the client and the server contains only the files of authorized clients.

What is DNS Caching?

DNS caching is the process of storing DNS data on DNS records that are closer to a requesting client in order to resolve the DNS query more rapidly. This avoids the issue of additional queries further down the chain while also improving web page load times and reducing bandwidth consumption.

The amount of time that DNS records are stored in the DNS cache is referred to as time to live (TTL). This time period is important because it determines how "fresh" the DNS records are and whether they match recent IP address updates.

DNS Caching can be done at two-level:

1) Browser DNS Caching

A DNS (Domain Name System) cache is a record of all queries made by your browser to a DNS server. When you enter a URL into your browser, it sends a request to the DNS server for the IP address of the URL. After receiving the IP address, your browser can load the correct website in your window.

2) Operating System (OS) Level DNS Caching

The DNS cache is a local storage location for DNS records kept by the operating system. The DNS cache stores the Resource Records (RR) of previously visited domains as well as their IP address translations. When you visit a website, your computer’s operating system performs a DNS lookup for the domain.

Working of DNS

DNS is a client/server network communication protocol. DNS clients send requests to the server, and DNS servers respond to the client.

Client requests containing a name that is converted into an IP address are known as forward DNS lookups, while requests containing an IP address that is converted into a name are known as reverse DNS lookups.DNS uses a distributed database to store the names of all the hosts on the internet.

Step 1: Every website is associated with a domain name/IP address.

Step 2: IP addresses are difficult to share (no one wants to type 18.164.246.23:443 or some random IP address to access prepbytes website ), people devised the concept of domain names, which basically store the IP address mapped to their name.

Step 3: A DNS now converts every domain name to its IP address, allowing any browser to access that specific website.

Step 4: DNS has simplified web surfing by allowing us to type prepbytes.com instead of some complicated 32-128 bit address to reach a website.

Types of DNS Server

There are mainly three types of DNS servers:

1) Primary Server

A primary DNS server serves as the first point of contact for a browser, application, or device that needs to convert a human-readable hostname to an IP address. A DNS record with the correct IP address for the hostname is stored on the primary DNS server.

2) Secondary Server

Secondary servers serve as backup DNS servers. During a zone transfer, secondary servers receive all of their zone files from the primary server’s zone files. For any given zone, multiple secondary servers can exist — as many as are required to provide load balancing, fault tolerance, and traffic reduction. Furthermore, any given DNS Server can act as a secondary server for multiple zones.

3) Cashing Server

Caching servers, also known as caching-only servers, do exactly what their name implies: they only provide cached-query service for DNS responses. Caching DNS Servers perform queries, cache the answers, and return the results to the querying client rather than maintaining zone files like other secondary servers. The primary distinction between caching servers and other secondary servers is that while other secondary servers maintain zone files (and perform zone transfers when necessary, generating network traffic in the process), caching servers do not.

How does DNS Increase Web Performance?

In today’s world where speed is everything, and everyone wants speed with the greatest accuracy possible. DNS uses caching to store the set of records or IP addresses returned by DNS queries for a set period of time in order to improve web performance. Caching increases efficiency by allowing servers to respond quickly when a request for the same IP address is received.

Let us use an example to better understand. After reading this article, suppose you want to return to scaler topics to read our fantastic articles. The IP address of the prepbytes topics is cached in your browser, and when you search for it the next day, the cache will pick it up instead of searching through multiple DNS servers. TTL refers to the amount of time a record is kept in the cache. Administrators determine a record’s time to live (TTL) based on a variety of variables. Longer periods reduce server load, while shorter periods provide the most precise responses.

Conclusion
The domain name system is a naming database that locates and translates internet domain names to their unique IP addresses, similar to how a phone’s contacts list matches names to numbers.DNS servers are classified into three types primary server, Secondary server, and Cashing server.
A domain name can be associated with more than one IP address. It is one of the primary reasons for using DNS.DNS caching seeks to reduce the amount of time it takes to receive a response to a DNS query. Phishing and cache poisoning are two major system vulnerabilities caused by DNS. We also conclude that dns cashing can be done at two levels, Browser DNS caching, and Operating system (OS)level DNS caching.

Frequently Asked Questions(FAQs)

Q1: what is a domain name system or DNS?
Ans: It is a hierarchical decentralized naming system for computers, services, or other resources connected to the internet or a private network. DNS translates domain names (such as example.com) into IP addresses (such as 93.184.216.34) that computers use to identify each other on the internet.

Q2: What is an IP address?
Ans: An IP address is a long string of numbers assigned to every device connected to a network that uses Internet Protocol as the medium of communication; it is the digital equivalent of your home or workplace mailing address.

Q3: What is a DNS resolver?
Ans: A DNS resolver is a software program that is responsible for converting domain names into IP addresses. When a user types a domain name into a web browser, the resolver sends a query to a DNS server to obtain the IP address associated with that domain name.

Q4: What is a DNS server?
Ans: A DNS server is a computer or network device that is responsible for translating domain names into IP addresses. DNS servers store records of domain names and their corresponding IP addresses and respond to DNS resolver queries to provide the correct IP address.

Q5: What is DNS propagation?
Ans: DNS propagation is the process of updating DNS records across the internet. When a DNS record is updated, it takes time for the updated record to be propagated to all DNS servers around the world. This can take anywhere from a few minutes to several days, depending on various factors such as the TTL (Time to Live) value of the DNS record and the configuration of the DNS servers involved.

Q6: What is a TTL (Time to Live) value?
Ans: TTL is a value that represents the amount of time a packet or data should exist on a computer or network before being discarded.

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