DNS Hierarchy Quiz

DNS Hierarchy

• The DNS hierarchy is a critical component of the Internet infrastructure, enabling users to access websites, send email, and communicate online.
• The root domain is the top-level of the DNS hierarchy, represented by a period (.) at the end of a domain name, and contains information about the top-level domains (TLDs).
• There are 13 root servers located around the world that manage the root domain, each with a unique IP address and responsible for responding to DNS queries for the root domain.

Root Domain Management

• The Internet Corporation for Assigned Names and Numbers (ICANN) is a nonprofit organization responsible for managing the root domain.
• ICANN oversees the operators of the root servers, known as the Root Zone Maintainer (RZM), who update the DNS root zone file, which contains information about the TLDs and their associated name servers.
• The root zone file is distributed to the 13 root servers, which respond to DNS queries for the root domain.

Top-Level Domains (TLDs)

• TLDs are the next level down in the DNS hierarchy after the root domain, and are used to categorize domain names based on their purpose or geographic location.
• There are two main types of TLDs: generic TLDs (gTLDs) and country-code TLDs (ccTLDs).
• Examples of gTLDs include .com, .org, .net, .info, .biz, .edu, and .gov, while examples of ccTLDs include .ma (Morocco), .us (United States), .uk (United Kingdom), .ca (Canada), .jp (Japan), and .au (Australia).

TLD Management

• gTLDs are managed by ICANN, which oversees the overall management of gTLDs and coordinates the selection and implementation of new gTLDs.
• ccTLDs are managed by designated country code registries, which are responsible for managing the domain names and associated name servers within their respective ccTLDs.
• The designated country code registry of Morocco is Agence Nationale de Réglementation des Télécommunications (ANRT).

Second-Level Domains

• Second-level domains are located immediately below the top-level domains (TLDs) in the DNS hierarchy, and are typically used to represent a particular entity or organization.
• A common second-level domain is google.

Domain Name Registration

• In order to use a domain name for a website or other online service, it must first be registered with a domain name registrar.
• The process of domain name registration involves selecting an available domain name, providing contact and other information, and paying a registration fee.
• Domain names can be registered for varying lengths of time, typically ranging from one to ten years.

Subdomains

• Subdomains are located below the second-level domains in the DNS hierarchy, and are used to further organize and specify a website's content or functionality.
• A subdomain is typically separated from the main domain by a period (.), and can include additional words or phrases to provide more context or specificity.
• Examples of subdomains include blog.example.com, shop.example.com, and support.example.com.

DNS and Subdomains

• Subdomains are an important part of the DNS system, allowing for more granular control and management of a website's content and functionality.
• Each subdomain can have its own DNS records, including A records, MX records, and CNAME records, which specify the IP address, mail server, and other details for that subdomain.

DNS Hierarchy in Action

• The DNS hierarchy is used to translate domain names into IP addresses, allowing users to access websites and other online services.
• When a user types in a domain name, their computer sends a DNS query to a DNS resolver, which begins the process of locating the IP address associated with that domain name.
• The DNS query starts at the root servers, which provide information about the top-level domains (TLDs), and then moves down the hierarchy to the authoritative name servers for the specific domain, which provide the IP address associated with that domain name.

DNS Cache

• The DNS hierarchy relies on caching to improve performance and reduce the load on DNS servers.
• When a DNS resolver receives a response to a DNS query, it stores that information in its cache for a specified period of time (known as the TTL or Time To Live).
• If another DNS query is made for the same domain name within the TTL period, the resolver can use the cached information rather than starting the DNS query process from scratch.