glossary.categories.networkingAcronym
DNS
Domain Name System
Domain Name System - translates human-readable domain names to IP addresses.
Definition
The Domain Name System (DNS) is the internet's phone book, translating human-readable domain names (like example.com) into IP addresses (like 93.184.216.34) that computers use to communicate. DNS is a hierarchical, distributed database system crucial to internet functionality. DNS issues can cause websites to become unreachable even when the servers themselves are running perfectly, making DNS monitoring essential for complete availability.
Examples
DNS Record Types
Common DNS record types and their purposes.
| Type | Purpose | Example |
|-------|--------------------------------|----------------------------|
| A | Maps domain to IPv4 | example.com -> 93.184.216.34 |
| AAAA | Maps domain to IPv6 | example.com -> 2001:db8::1 |
| CNAME | Alias to another domain | www -> example.com |
| MX | Mail server for domain | mail.example.com (10) |
| TXT | Text records (SPF, DKIM, etc.) | v=spf1 include:... |
| NS | Nameservers for domain | ns1.provider.com |DNS Lookup Process
How a DNS query is resolved.
1. User types example.com in browser
2. Browser checks local cache
3. Query sent to recursive resolver (ISP or 8.8.8.8)
4. Resolver queries root nameservers (.)
5. Root refers to .com TLD nameservers
6. TLD refers to example.com's authoritative NS
7. Authoritative NS returns IP address
8. Browser connects to 93.184.216.34Use Cases
Website and service accessibility
Email delivery (MX records)
Load balancing across servers
Failover and disaster recovery
Best Practices
- Use multiple DNS providers for redundancy
- Set appropriate TTL values
- Monitor DNS resolution from multiple locations
- Enable DNSSEC for security
- Document all DNS records and their purposes
FAQ
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