How DNS Works - Computerphile

TL;DR

DNS is a system that helps resolve domain names to IP addresses so that users can access websites on the internet.

Transcript

so i thought today we talked about dns or the domain name system um this is a service that runs on all of our computers um but obviously it's run mostly over the internet by big servers the idea is that we want to try and resolve ip addresses to domain names for example i go to youtube.com then at some point i'm going to have to work out what the i... Read More

Key Insights

• 👤 DNS is a crucial system that translates domain names to IP addresses, enabling users to access websites easily.
• 🛟 Name servers play a vital role in the DNS resolution process by querying other authoritative name servers to find the IP address.
• 🤐 Caching helps improve DNS performance by storing recently accessed domain names and their corresponding IP addresses.
• 🛟 Root name servers are globally distributed and serve as the starting point for DNS queries.
• 🛟 Recursive resolvers can not only answer DNS queries but also make queries to other name servers if necessary.
• 💁 DNS cache poisoning is a potential security threat where incorrect information is injected into a DNS cache.
• 🍵 DNS is a distributed database that handles a massive number of queries every second.

Questions & Answers

Q: What is DNS and why is it important?

DNS, or the Domain Name System, is a system that translates domain names into IP addresses, allowing users to access websites on the internet. It is important because it simplifies the process of accessing websites and eliminates the need for users to remember complex IP addresses.

Q: How does DNS resolve a domain name to an IP address?

When a user enters a domain name, their computer sends a DNS query to a name server. The name server will then contact other authoritative name servers, starting with root name servers, to find the IP address associated with the domain name. This process continues until the IP address is found.

Q: What happens if a name server does not have the IP address for a domain name?

If a name server does not have the IP address for a domain name, it will contact other name servers that it thinks might know the answer. This process continues until the IP address is found or a "couldn't find the domain" message is returned.

Q: How does caching work in DNS?

DNS caching allows for faster access to frequently visited websites. Both the user's computer and the name server involved in the DNS resolution process have caches. If a domain name has been recently accessed, it will be stored in the cache, and subsequent requests for that domain will be served directly from the cache, reducing the time needed for resolution.

Summary & Key Takeaways

• DNS is a service that helps resolve IP addresses to domain names, allowing users to access websites on the internet.

• When a user enters a domain name, their computer sends a DNS query to a name server to find the corresponding IP address.

• The name server will contact root name servers and other authoritative name servers to find the IP address, ultimately allowing the user to communicate with the desired server.