DNS in Computer Network

Last Updated on April 13, 2023 by Prepbytes

The DNS in Computer Networks is a crucial component that enables the identification and mapping of internet resources such as IP addresses, domain names, and other critical network-related information. This article discusses what is DNS in computer networks, the working of DNS in computer networks, types of DNS servers, types of DNS queries, DNS caching, etc. So, without any further delay, lets us immediately move to our next section which is what is DNS in Computer Networks.

What is DNS in Computer Networks?

The DNS in computer networks is a hierarchical and distributed naming system. DNS is responsible for translating human-readable domain names into machine-readable IP addresses, allowing devices on a network to communicate with each other efficiently.

In a typical scenario, when a user types a domain name into their web browser, the browser sends a request to a DNS resolver or recursive resolver, usually provided by the user’s internet service provider (ISP). The DNS resolver then sends a query to the DNS root server to find the authoritative name server for the domain in question. The authoritative name server responds with the IP address associated with the domain name, which is then sent back to the DNS resolver and eventually to the user’s browser. This process is known as DNS resolution.

DNS servers are responsible for converting alphabetic domain names to their corresponding IP addresses. The DNS resolution process can be iterative or recursive, depending on how the DNS resolver handles the request.

1. Recursive DNS Service
   Recursive DNS service refers to the process of resolving a domain name by sending a request to a DNS resolver, which will recursively query other DNS servers until it finds the authoritative server that can provide the IP address for the requested domain name. In this process, the DNS resolver acts on behalf of the client and handles all the iterative queries to find the necessary information to resolve the domain name.

2. Iterative DNS Service
   Iterative DNS service is a process of resolving a domain name by querying DNS servers one by one until the authoritative server is found. In this process, the DNS resolver sends iterative queries to different DNS servers, and each server responds with the best answer it can provide, such as a referral to another server or the IP address of the requested domain name. The DNS resolver then uses this information to continue querying other DNS servers until it finds the authoritative server that can provide the final answer.

How does DNS in Computer Networks Work?

DNS in computer networks is responsible for converting a domain name into an IP address. Let’s take a look at the following steps.

• Step 1 – User requests DNS resolution: A user types a domain name into their web browser, such as www.PrepBytes.com, and hits enter.
• Step 2 – DNS resolver sends query: The user’s computer sends a request for DNS resolution to a DNS resolver or recursive resolver, usually provided by the user’s internet service provider (ISP).
• Step 3 – Querying Root DNS Servers: The recursive resolver then sends a query to the DNS root server to find the authoritative name server for the top-level domain of the domain name. The root servers provide the IP addresses for the top-level domain name servers, which are responsible for resolving domain names for their corresponding top-level domains.
• Step 4 – Querying TLD DNS Servers: The recursive resolver then sends a query to the top-level domain (TLD) name server to find the authoritative name server for the second-level domain of the domain name. For example, if the domain name is www.PrepBytes.com, the TLD name server for .com is queried.
• Step 5 – Querying Authoritative DNS Server: The recursive resolver then sends a query to the authoritative name server for the second-level domain to find the IP address associated with the domain name.
• Step 6 – DNS resolution response: The authoritative name server responds with the IP address associated with the domain name. This information is sent back to the recursive resolver, and then back to the user’s computer.
• Step 7 – User accesses website: The user’s computer uses the IP address to connect to the web server hosting the website associated with the domain name, and the website is displayed in the user’s web browser.

Types of DNS Servers in Computer Networks

There are primarily four types of DNS servers in computer networks:

1. Recursive Resolver: A recursive resolver is a DNS server that queries other DNS servers on behalf of the requesting client until it finds the IP address associated with the requested domain name. Most internet service providers (ISPs) provide a recursive resolver for their customers to use.

2. Root Name Server: The root name servers are the first point of contact in the DNS resolution process. There are 13 root name servers in the world, each with a unique IP address, and they are responsible for responding to queries about the location of the top-level domain (TLD) name servers.

3. TLD Name Server: The TLD name servers are responsible for resolving queries about the location of authoritative name servers for the specific TLD they are responsible for. For example, the TLD name server for .com would be responsible for resolving queries about the location of authoritative name servers for domains that end in .com.

4. Authoritative Name Server: The authoritative name server is the DNS server that holds the IP address associated with a specific domain name. When a recursive resolver queries an authoritative name server, it provides the IP address associated with the requested domain name.

Types of DNS Queries in Computer Networks

DNS queries are requests sent by client devices to DNS servers to obtain information about domain names, IP addresses, and other resource records associated with a domain. There are three types of DNS queries in computer networks, including:

1. Recursive Query: A recursive query is a request made by a client to a DNS server to obtain the requested information. If the DNS server does not have the information, it will initiate a recursive query to other DNS servers until the information is found or it is determined that the information does not exist.

2. Iterative Query: An iterative query is a request made by a client to a DNS server to obtain the requested information. If the DNS server does not have the information, it will return a referral to the client, which contains the address of another DNS server that may have the information.

3. Nonrecursive Query: A nonrecursive query is a request made by a client to a DNS server to obtain the requested information. If the DNS server does not have the information, it will return a referral to the client, which contains the address of another DNS server that may have the information. However, unlike an iterative query, the DNS server will not perform any further lookups on behalf of the client.

Common DNS Record

DNS records are used to store information about a domain name and its associated IP address(es). Some of the most common DNS record types include:

1. A Record (Address Record): An A record maps a domain name to its corresponding IP address. For example, if a user types "www.example.com" into their web browser, the A record associated with that domain name would provide the IP address of the web server hosting the website.

2. CNAME Record (Canonical Name Record): A CNAME record maps an alias or subdomain to its corresponding domain name. For example, a CNAME record might map "blog.example.com" to "www.example.com", allowing users to access the blog using a subdomain of the main website.

3. MX Record (Mail Exchange Record): An MX record specifies the mail server responsible for accepting incoming email messages for a domain name.

4. NS Record (Name Server Record): An NS record specifies the authoritative name servers for a domain name.

5. TXT Record (Text Record): A TXT record can be used to store any text-based information related to a domain name, such as SPF (Sender Policy Framework) records used for email authentication.

These are just a few examples of the many types of DNS records that are used to store information about a domain name and its associated IP address(es).

How does DNS in Computer Networks increase Web Performance?

In today’s world where speed is everything, and everyone wants speed with the greatest accuracy possible. DNS in computer networks 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 PrepBytes to read our fantastic articles. The IP address of the PrepBytes 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.

DNS Caching

DNS caching is the process of temporarily storing DNS lookup results on a local device or server for future reference. When a device or application needs to access a particular domain name, it first checks its local cache to see if it has recently looked up the IP address associated with that domain name. If the information is available in the cache, the device can skip the DNS resolution process and access the requested domain name directly, which can help to speed up the overall process.

DNS caching is performed by both DNS resolvers (such as those provided by ISPs) and by individual devices, such as computers, smartphones, and routers. The time that DNS records are cached can vary depending on a number of factors, including the time-to-live (TTL) value set by the authoritative name server, the configuration of the caching DNS resolver, and the behavior of the local device or application.

DNS caching can be done in various places, including:

1. Operating System: Most modern operating systems have a DNS cache built-in. When a user requests a domain name, the operating system checks its cache first before querying a DNS resolver. This can speed up the process of resolving domain names and reduce network traffic.

2. Web Browsers: Web browsers also have their own DNS cache, which stores information about the domain names of recently visited websites. This can help to speed up the loading of web pages and reduce the number of DNS requests that need to be made.

3. DNS Resolver: DNS resolvers, such as those provided by Internet Service Providers (ISPs) or third-party services like Google DNS, also perform caching. When a DNS resolver receives a request for a domain name, it first checks its cache to see if it has the corresponding IP address. If the information is available in the cache, the resolver returns it to the requester without having to perform a new DNS lookup.

Domain Name Space

Domain Name Space refers to the hierarchical naming system used to organize domain names on the internet. It is divided into levels, with each level separated by a dot. The top-level domain (TLD) is the highest level in the hierarchy, and it is followed by the second-level domain, subdomain, and hostname.

DNS in computer networks organizes the domain name space into a tree-like structure, with the root at the top, followed by the TLDs, second-level domains, and so on. The root domain represents the top of the tree and is represented by a single dot. The TLDs are divided into two types: generic TLDs (gTLDs), such as .com, .org, and .net, and country-code TLDs (ccTLDs), such as .uk, .au, and .cn.

The second-level domains are the domain names registered by individuals, organizations, or businesses. They can be further divided into subdomains, which are used to organize different parts of a website or network. Finally, the hostname is the specific name assigned to a particular computer or device within a domain.

Conclusion
In conclusion, DNS in computer networks plays a crucial role in the functioning of the internet by translating domain names into IP addresses. The DNS resolution process involves multiple steps and servers, but the end result is that users are able to access the websites and resources they need. DNS caching also helps to improve performance and reduce network traffic, but it is important to keep the cache up-to-date to avoid potential issues. Overall, DNS in computer networks is a fundamental technology that enables the internet to function as we know it today.

FAQs Related to DNS

Here are some frequently asked questions on DNS in Computer Networks.

Q1: What is DNS in Computer Networks?
Ans: DNS in computer networks is a hierarchical decentralized naming system for computers, services, or other resources connected to the internet or a private network. DNS in computer networks 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.