The Domain Name System (DNS) is like the internet's phone book. It translates human-readable domain names (e.g., www.example.com) into machine-readable IP addresses (e.g., 192.0.2.1), allowing you to access websites easily.
How DNS Works
1. User Request
- You type a website URL (e.g.,
www.example.com) into your browser.
2. DNS Query
- Your computer sends a DNS query to a DNS resolver (usually provided by your internet service provider).
3. DNS Resolver Checks Cache
- The resolver may already know the IP address and respond quickly, or it may need to ask other DNS servers.
4. Root DNS Servers
- If needed, the resolver asks the root DNS servers where to find information about the domain.
5. TLD DNS Servers
- The root server directs the resolver to the Top-Level Domain (TLD) servers (e.g.,
.com, .org).
6. Authoritative DNS Servers
- The resolver finally asks the authoritative DNS server for the domain, which holds the correct IP address.
7. Connection
- Your device receives the IP address and uses it to connect to the website server.
Common DNS Records
- A Record: Links a domain to an IPv4 address (e.g.,
www.example.com -> 192.0.2.1).
- MX Record: Directs email to mail servers for the domain.
- CNAME Record: Points a domain to another domain (e.g.,
blog.example.com -> example.com).
- NS Record: Specifies which DNS servers handle the domain.
- TXT Record: Stores text info like email verification (e.g., SPF, DKIM).
DNS Caching
- Local Cache: Your computer remembers DNS info to speed up future requests.
- ISP Cache: Your internet service provider might store DNS info for faster access.
- Authoritative Cache: The authoritative server stores DNS info for a set period.
DNS Propagation
When DNS records are updated, changes take time to spread across the internet. This can take from a few minutes to 48 hours.
Conclusion
DNS helps convert website names into IP addresses, making it possible to access websites easily.
