DNS Lab: A Record, Local Cache, and CNAME Testing in Active Directory

Overview

This lab demonstrates the behavior of DNS records in a domain environment, including A records, DNS caching, and the use of CNAME records. Testing was done using Azure-hosted virtual machines configured as a domain controller (DC-1) and a domain-joined client (Client-1).

Technologies Used

• Microsoft Azure (VM deployment)
• Windows Server (Domain Controller)
• Active Directory DNS
• DNS Records (A-Record, CNAME)
• DNS Client Tools (nslookup, ipconfig)
• DNS Cache Management

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1. A Record Creation and Testing

Logged into:

• DC-1 as mydomain.com\jane_admin
• Client-1 as mydomain\jane_admin

On Client-1:

• Attempted to ping mainframe → Request failed
• Ran nslookup mainframe → No DNS record found

On DC-1:

• Created a DNS A Record for mainframe
• Pointed the A record to DC-1's Private IP Address

Back on Client-1:

• Pinging mainframe now succeeded, confirming that the DNS record propagated correctly

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2. DNS Cache Behavior

On DC-1:

• Modified the existing A record for mainframe, changing the IP address to 8.8.8.8

Back on Client-1:

• Pinged mainframe again → Still resolved to the old IP address
• Ran ipconfig /displaydns → Confirmed the outdated address was cached locally

To refresh:

• Executed ipconfig /flushdns to clear the local DNS cache
• Verified cache clearance with ipconfig /displaydns
• Pinged mainframe again → Now resolved to the updated address (8.8.8.8)

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3. CNAME Record Creation and Testing

On DC-1:

• Created a CNAME Record: aliased search to www.google.com

On Client-1:

• Pinging search resolved to Google's public address, showing successful aliasing
• Ran nslookup search → Confirmed that the CNAME record correctly redirected to www.google.com

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Skills and Experience Gained

This lab provides foundational hands-on experience in Active Directory-integrated DNS management, a critical skill for system and network administrators. Key competencies developed include:

• Creating and troubleshooting A Records for internal name resolution
• Observing and managing DNS client-side caching behavior
• Configuring CNAME (alias) records for flexible DNS mappings
• Using tools like ping, nslookup, and ipconfig to validate DNS functionality and diagnose issues
• Understanding the propagation and caching process of DNS records in enterprise environments

These skills are essential for managing scalable, secure networks and play a key role in IT operations, cybersecurity, and cloud administration.

Screenshots

All screenshots for this lab can be found in the screenshots folder.