Quick answer: DNS connects domain names to website and email services. Different records handle different jobs: A and AAAA records point to IP addresses, MX records control inbound mail, and TXT records can contain email authentication policies. For the details, read our DNS record types guide and SPF, DKIM and DMARC tutorial.
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.
Next: common DNS record types
Once you understand DNS lookups, explore our DNS record types guide for an explanation of A, MX, CNAME, NS and TXT records.
Conclusion
DNS helps convert website names into IP addresses, making it possible to access websites easily.
How DNS caching affects changes
A DNS resolver may keep a previous answer until its time-to-live period expires. This means different visitors may briefly reach different destinations after a DNS change. Check that you edited the active authoritative DNS zone and avoid making repeated changes while waiting for caches to refresh.
If your website and email are hosted separately, keep the appropriate MX and email authentication records when adjusting web records. For practical troubleshooting, see DNS propagation explained.