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1 COMPUTER NETWORKING MCQS

DNS (Domain Name System) operates at which OSI layer?

  • Network Layer
  • Data Link Layer
  • Application Layer
  • Transport Layer
Correct Answer: C. Application Layer

Detailed Explanation

DNS (Domain Name System) operates at the Application Layer of the OSI model. This is the topmost layer, which provides services directly to the user or applications.

DNS is responsible for resolving human-readable domain names (like www.example.com) into IP addresses (like 192.0.2.1) that computers can use to identify each other on the internet or a private network.



Here how DNS works in simple steps:



  • The user types a web address into their browser.

  • The browser asks DNS to find the IP address linked to that domain name.

  • DNS looks through a database of domain names and their corresponding IP addresses.

  • Once it finds the correct IP, it sends it back to the browser.

  • The browser then uses that IP to connect to the website.



Key Points about DNS:



  • DNS makes it easier for users to access websites without remembering IP addresses.

  • It acts like a phonebook for the internet.

  • DNS queries use the UDP protocol by default (port 53), and sometimes TCP for larger responses.



Conclusion: DNS is a core part of the internet and works at the Application Layer of the OSI model. It provides name resolution services that make user-friendly web browsing possible. This makes DNS a very important topic for both interviews and networking exams.

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