What is DNS and Types of DNS Records with Commands to Query Print

What is DNS?

DNS (Domain Name System) is the protocol that translates human-readable domain names (like example.com) into IP addresses (like 192.168.1.1), enabling browsers to connect to websites. It acts like the phonebook of the Internet.

Why is DNS Important?

• Enables users to access websites without needing IP addresses.
• Facilitates fast, efficient routing of traffic between users and servers.
• Essential for services like email delivery and authentication.

Types of DNS Records and Their Utilities

• A Record: Maps a domain to an IPv4 address (e.g., example.com → 93.184.216.34).
• AAAA Record: Maps a domain to an IPv6 address.
• CNAME Record: Creates an alias for another domain (e.g., www.example.com → example.com).
• MX Record: Directs email to mail servers (e.g., example.com → mail.example.com).
• NS Record: Specifies the authoritative DNS servers for a domain.
• TXT Record: Holds arbitrary text data for verification or security (e.g., SPF or DKIM records).
• PTR Record: Maps an IP address back to a domain (reverse DNS lookup).
• SOA Record: Stores essential information about a domain, including its primary name server and refresh times.

Commands to Query DNS Records

Windows

1. Open Command Prompt (Search "cmd" and open).
2. Run:

   nslookup example.com

3. For a specific record type (e.g., MX):

   nslookup -query=MX example.com

macOS / Linux

1. Open Terminal.
2. Use the dig command:

   dig example.com

3. Query specific records:

   dig example.com MX

4. For reverse DNS lookup:

   dig -x 93.184.216.34

Web-Based DNS Tools

• DNSChecker: Look up DNS records globally.
• Google Admin Toolbox: DNS troubleshooting tools.

Troubleshooting Tips

• If DNS changes are not reflected, try flushing your DNS cache using:

  ipconfig /flushdns (Windows) or sudo dscacheutil -flushcache (macOS).

• Ensure your domain is using the correct name servers (NS Records).
• Check propagation delays using DNSChecker.