How a DNS Server (Domain Name System) works.

Summary

The video explains how the Domain Name System (DNS) allows computers and humans to communicate effectively despite using different methods of identification. While computers rely on IP addresses to connect with each other, humans use easy-to-remember domain names like 'yahoo.com'. DNS acts as a translator, converting domain names into IP addresses so that computers can interact. The process involves multiple stages, including requests to the resolver server, root servers, TLD servers, and authoritative name servers, which ultimately provide the necessary IP address for accessing websites.

Takeaways

• 😀 Computers use numbers, such as IP addresses, to identify each other over a network, while humans use names.
• 😀 DNS (Domain Name System) was developed to bridge the communication gap between human-friendly names and computer-understood numbers.
• 😀 DNS resolves domain names (like yahoo.com) to IP addresses, allowing computers to find websites on the internet.
• 😀 Humans can use domain names instead of memorizing complex IP addresses to access websites more easily.
• 😀 DNS acts like a phone book, translating names into corresponding numbers (IP addresses) for computers to communicate.
• 😀 When a user types a domain name in a browser, DNS first checks its local cache to see if the IP address is stored.
• 😀 If the IP address is not in the cache, the query is sent to a resolver server, typically managed by the Internet Service Provider (ISP).
• 😀 The resolver server queries the root servers if it can't find the address in its own cache. These root servers know where to find TLD servers.
• 😀 TLD (Top-Level Domain) servers manage information for domain categories like .com, .net, .org, and direct queries to authoritative name servers.
• 😀 Authoritative name servers are the final source of truth for an IP address, providing the correct IP for a domain name like yahoo.com.
• 😀 Once the IP address is resolved, the resolver stores it in its cache to improve response time for future requests to the same domain.

Q & A

Why do computers use numbers instead of names for communication over a network?

Computers and other devices communicate over a network using numbers, such as IP addresses, because they are designed to process numeric values. Numbers are more efficient for machines to handle and identify each other compared to names, which are more suited for human understanding.

What is DNS and how does it bridge the gap between human-friendly names and computer-friendly numbers?

DNS, or Domain Name System, is a system developed to resolve domain names to IP addresses. It allows humans to use easy-to-remember names for websites (like yahoo.com) while computers communicate using IP addresses, making web navigation simpler for users.

Can you access a website without typing the domain name? If so, how?

Yes, you can access a website by typing the IP address directly into your browser instead of the domain name. However, since memorizing IP addresses for millions of websites is impractical, DNS allows users to input the domain name, and it automatically resolves it to the corresponding IP address.

How does DNS work when you type a domain name into a web browser?

When you type a domain name, like yahoo.com, into your browser, the system first checks its own cache for the IP address. If it can't find it, the query is sent to a DNS resolver, which then queries other servers (root, TLD, and authoritative servers) to resolve the IP address.

What role do DNS resolver servers play in the DNS process?

DNS resolver servers, typically provided by your ISP, are responsible for processing DNS queries. When a query is made for a domain name, the resolver searches its cache for the IP address. If it doesn't find it, the resolver sends the query to higher-level servers for further resolution.

What are root servers in the context of DNS and what is their role?

Root servers are the highest level in the DNS hierarchy and are responsible for directing DNS resolvers to the appropriate Top-Level Domain (TLD) servers. There are 13 sets of root servers around the world, and they do not know specific domain IPs but know where to send queries for further resolution.

What are TLD servers and how do they contribute to DNS resolution?

TLD servers manage domain extensions such as .com, .net, and .org. When a resolver queries for a domain like yahoo.com, the TLD server for the .com domain will direct the resolver to the authoritative name servers, which contain the specific IP address for the domain.

What is the function of authoritative name servers in DNS?

Authoritative name servers are responsible for knowing the exact IP addresses of domains. Once a resolver reaches an authoritative name server, it retrieves the specific IP address for a domain, such as yahoo.com, and returns it to the user's computer for webpage retrieval.

How does DNS improve the efficiency of web browsing for users?

DNS improves web browsing efficiency by allowing users to type human-readable domain names instead of remembering numeric IP addresses. It also caches IP addresses locally to reduce lookup times, making subsequent visits to websites faster.

What happens if a DNS resolver cannot find a domain's IP address in its cache?

If a DNS resolver cannot find the domain's IP address in its cache, it will query higher-level servers, starting with the root server, then the TLD server, and finally the authoritative name server, to obtain the correct IP address for the domain.