What is DNS and how does it work ?

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– DNS ⇒ The Domain Name System

– The Domain Name System (DNS) is a protocol that translates the domain names we use daily.

ex) w= ⇒ 142.250.72.238

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– Query :

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When you enter a website address into your browser,

⇒ the browser sends a request to a DNS server to look up the IP address associated with that name.

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– DNS Basics and Its Role in the Internet :

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⇒ Root Servers :

These servers contain information about top-level domains (TLDs) [like .com, .org and .edu].

⇒ TLD Servers :

These servers hold information about domain names within (specific) TLDs like .com or .org.

– Root Servers ⇒ are the first stage that directs requests to TLD servers.

– TLD Servers ⇒ then direct requests to the authoritative name servers for the specific domain.

– Each level plays an important role in translating a domain name into an IP address, which helps in efficiently directing internet traffic.

⇒ Authoritative Name Servers :

– These servers contain (accurate information) about specific domains (like [google.com]).

⇒ Local Resolver (DNS Resolver) :

– This is usually a server maintained by your (ISP) ⇒ that responds to user queries first.

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Overview of DNS Resolution Steps :

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1) The browser sends a request to the local “DNS resolver”.

2) If the “local resolver” doesn’t know the answer, it forwards the request to a “root server”.

3) The “root server” directs the query to the appropriate “TLD server”.

4) The “TLD server” then directs the query to the “authoritative name server” that knows the correct IP address.

5) The IP address is returned to “the browser”, which then connects to the server hosting the website.

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– Caching :

To speed up the process, DNS queries are cached for a certain period, reducing the need for repeated lookups.

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– there are several types of DNS records that provide different information about a domain. Here are the main types :

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⇒ A Record (Address Record):

– Links a domain name to an (IPv4) address of a web server.

might have an A record pointing to [192.0.1.2].

⇒ AAAA Record (IPv6 Address Record):

– Links a domain name to an (IPv6) address.

might have an AAAA record pointing to [2002:db6::1].

⇒ MX Record (Mail Exchange Record):

– Specifies the mail servers responsible for receiving emails for a domain.

⇒ CNAME Record (Canonical Name Record):

– Maps a domain name to another domain name, allowing you to alias one domain to another.

⇒ NS Record (Name Server Record):

– Defines the DNS servers responsible for a domain.

⇒ TXT Record (Text Record):

– Allows adding text information to DNS records, often used for domain verification or storing SPF records.

– It might include information about email policies.

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– Importance of DNS:

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⇒ It allows us to use easy-to-remember names instead of complex IP addresses.

⇒ It plays a vital role in routing internet traffic.

⇒ It can be exploited in cyberattacks [like “DNS Spoofing,” which can redirect users to malicious websites].

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هذا فما كان من توفيق فمن الله وما كان من خطأ أو سهو أو زلل أو نسيان فمني و من الشيطان.

و صلى الله و سلم على نبينا محمد ﷺ