What Is DNS?

DNS (Domain Name System) is a distributed naming system that translates domain names (e.g., example.com) into IP addresses (e.g., 192.0.2.1).

Without DNS, accessing internet services using human-readable names would not be possible. DNS is a foundational component of network communication.

How Does DNS Resolution Work?

When a domain name is requested, the DNS resolution process follows these steps:

• The client queries the configured DNS server
• The DNS server looks up the IP address
• If found, the IP address is returned to the client
• The client connects to the resolved IP address

Where Are DNS Settings Configured on Linux?

On Linux systems, DNS settings are commonly defined in:

/etc/resolv.conf

Typical entries include:

nameserver 8.8.8.8
nameserver 1.1.1.1
search example.local

What Is systemd-resolved?

Modern Linux distributions may use systemd-resolved to manage DNS resolution.

This service provides DNS caching, fallback servers, and interface-based DNS configurations.

DNS Troubleshooting Tools

The following tools are commonly used to diagnose DNS issues:

• dig: Detailed DNS query analysis
• nslookup: Simple DNS queries
• ping: Verifies name-to-IP resolution

Example dig Usage

dig example.com
dig example.com A
dig example.com MX

Common DNS Issues

• Incorrect or unreachable DNS servers
• Cached stale DNS records
• Misconfigured DNS records (A, MX, CNAME)
• Firewall or network restrictions

Best Practices

• Configure multiple DNS servers
• Monitor DNS cache behavior
• Enable logging for critical systems
• Consider TTL values after DNS changes

From a knowledge base perspective, DNS management is a core requirement for network availability and service continuity.