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.
