DNS

Created: 2025-11-25 Tags: networking dns protocols name-resolution

Description

DNS (Domain Name System) translates human-readable domain names into IP addresses. It’s a critical internet service and common attack target.

Key Concepts

• Hierarchical distributed database
• Port 53 (UDP for queries, TCP for zone transfers)
• Resolves names to IPs and vice versa
• Caching for performance

DNS Record Types

• A: IPv4 address
• AAAA: IPv6 address
• CNAME: Canonical name (alias)
• MX: Mail exchange
• NS: Name server
• TXT: Text records
• PTR: Reverse DNS lookup
• SOA: Start of authority

Security Concerns

Attacks

• DNS spoofing/poisoning
• DNS tunneling (data exfiltration)
• DDoS amplification
• Cache poisoning
• DNS hijacking

Protections

• DNSSEC (DNS Security Extensions)
• DNS over HTTPS (DoH)
• DNS over TLS (DoT)
• Rate limiting
• Monitoring and logging

Related Topics

• DHCP
• nslookup
• dig
• Threat Hunting

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