DNS

The Domain Name System is a hierarchical and distributed naming system for computers, services, and other resources in the Internet or other IP networks. It associates various information with domain names assigned to each of the associated entities. It resolves an FQDN to an IP address

Resolved on Layer 3
Port 53 TCP/UDP

Record types

1. A (Address Record)
   1. Maps a domain to an IPv4 address
2. AAAA (IPv6 Address Record)
   1. Maps a domain to an IPv6 address
3. CNAME (canonical name)
   1. Configures an alias for a domain (e.g., \www.example.com CNAME example.com)
4. MX (Mail Exchange)
   1. Defines the mail server responsible for receiving mail for that domain
5. TXT
   1. Holds text information, like SPF records
   2. Often used for verification
6. NS (Name Server)
   1. Specifies the authoritative DNS servers for the domain
7. PTR (Pointer record)
   1. Used for reverse DNS lookups
8. SOA (Start of Authority)
   1. Provides information about the domain
9. SRV (service record)
   1. Specifies location of servers for specific services, like SIP or IMAP
10. CAA (Certification Authority Authorization)
    1. Specifies which CAs are allowed to issue certificates for the domain

Metadata

OSI or TCP/IP Layer

CCNA Exam Topic

#extops-4-3

Contributors

Sources

Domain Name System - Wikipedia
What are DNS records? | Cloudflare
DNS Records Explained | Gcore