DNS MCQ Quiz in বাংলা - Objective Question with Answer for DNS - বিনামূল্যে ডাউনলোড করুন [PDF]

DNS: (Domain Name System)

• The Domain Name System is a hierarchical and decentralized naming system for computers, services, or other resources connected to the Internet or a private network.
• DNS protocol is used for Domain names to IP Address mapping.

HTTP: (Hypertext Transfer Protocol)

• It is an application-layer protocol for transmitting hypermedia documents, such as HTML.
• It was designed for communication between web browsers and web servers, but it can also be used for other purposes

SMTP: (Simple Mail Transfer Protocol)

• SMTP is used when email is delivered from an email client, such as Outlook Express, to an email server or when email is delivered from one email server to another.
• SMTP uses port 25.

POP (Post Office Protocol)

• POP is a type of computer networking and Internet standard protocol that extracts and retrieves email from a remote mail server for access by the host machine.

FTP (File Transfer Protocol)

• FTP stands for file transfer protocol. It is provided by TCP/IP for copying a file from one host to another. FTP can transfer a file through one of the following three modes: stream mode, block mode and compressed mode. Stream mode is the default mode.
• FTP uses two TCP connections one for data and another for control.

Therefore option 2, 3, and 4 does not match.

Domain Name System (DNS)

• The Domain Name System (DNS) is a hierarchical and decentralized naming system for computers, services, or other resources connected to the Internet or a private network.
• It associates various information with domain names assigned to each of the participating entities.
•  It translates more readily memorized domain names to the numerical IP addresses needed for locating and identifying computer services and devices with the underlying network protocols.

Domain Name:

A domain name is a label that identifies a network domain: a distinct group of computers under a central administration or authority

Company managing the reservation of domain names is domain name registrar

A domain name registry is a database of all domain names and the associated registrant information in the top-level domains of the Domain Name System (DNS)

Domain registration is the process of acquiring a domain name from a domain name registrar

Explanation:

DNS uses TCP for zone exchanges between servers and UDP when a client is trying to resolve a hostname to an IP address.

1. The Domain Name System (DNS) is the phonebook of the Internet. Humans access information online through domain names, like nytimes.com or espn.com. Web browsers interact through Internet Protocol (IP) addresses. DNS translates domain names to IP addresses so browsers can load Internet resources.

2. Each device connected to the Internet has a unique IP address that other machines use to find the device. DNS servers eliminate the need for humans to memorize IP addresses such as 192.168.1.1 (in IPv4), or more complex newer alphanumeric IP addresses such as 2400:cb00:2048:1::c629:d7a2 (in IPv6).

Working of DNS:

• When a user types a human-readable address into the browser, the operating system’s DNS client will check for information in a local cache. If the requested address isn’t there, it will look for a Domain Name System server in the local area network (LAN). When the local DNS server receives the query, and the requested domain name is found, it will return the result.
• If the name is not found, the local server will forward the query to a DNS cache server, often provided by the Internet Service Provider (ISP). Since the DNS server’s cache contains a temporary store of DNS records, it will quickly respond to requests. These DNS cache servers are called not authoritative DNS servers as they provide request resolution based in a cached value acquired from authoritative DNS servers.

Confusion Points

Some Standard books say that DNS uses UDP only, But in implementation DNS also using TCP as well.

Concept:

A valid email address consists of an email prefix and an email domain, both in acceptable formats. The prefix appears to the left of the @ symbol. The domain appears to the right of the @ symbol. For example, in the address [email protected], "name" is the email prefix, and "website.com" is the email domain

The three parts of an Email Address are:

• Username - The first part of an email address is the username.
• @ Symbol -  An “at,” or “@,” symbol is the second part of an email address.
• Domain - The last part of an email address is the domain, which can be broken down into two portions: the mail server and the top-level domain.

Hence Option 2 is correct