DNS Record Management and Cache Clearing

This tutorial will guide you through managing DNS records and understanding DNS cache behavior using Active Directory and client machines. You’ll create and test DNS A and CNAME records, handle DNS cache, and verify changes.

Environments and Technologies Used

• Microsoft Azure (Virtual Machines)
• Microsoft RD Client (Remote Desktop)

Operating Systems Used

• macOS Sonoma (if you own Macbook Air M1 or M2; it does not matter what type of macOS you own)
• Windows 10 or Windows 11 Home or Pro (if you own either of these OS)

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1. A-Record Exercise

1. Log In to DC-1:

   • Use your domain admin account (e.g., mydomain.com\jane_admin).

2. Log In to Client-1:

   • Use the same admin account (e.g., mydomain\jane_admin).

3. Ping Test:

   • On Client-1, attempt to ping mainframe. Note that it fails.

4. Nslookup Test:

   • On Client-1, perform nslookup mainframe. It will fail due to the absence of a DNS record.

5. Create A-Record:

   • On DC-1, create a DNS A-record for mainframe pointing to DC-1’s private IP address.

6. Verify:

   • On Client-1, ping mainframe again. It should now resolve successfully.

2. Local DNS Cache Exercise

1. Change DNS Record:

   • On DC-1, update the A-record for mainframe to point to 8.8.8.8.

2. Ping Test:

   • On Client-1, ping mainframe and observe that it still resolves to the old IP address.

3. Check Cache:

   • On Client-1, use ipconfig /displaydns to view the local DNS cache.

4. Flush DNS Cache:

   • Run ipconfig /flushdns on Client-1 to clear the DNS cache.

5. Verify:

   • Attempt to ping mainframe again. The ping should now resolve to the new IP address (8.8.8.8).

3. CNAME Record Exercise

1. Create CNAME Record:

   • On DC-1, create a CNAME record for search pointing to www.google.com.

2. Ping Test:

   • On Client-1, ping search and observe that it resolves to www.google.com.

3. Nslookup Test:

   • On Client-1, perform nslookup search and verify that it shows the CNAME record pointing to www.google.com.

Conclusion

By the end of this guide, you should know or understand how to manage DNS records by creating A and CNAME records, and handling DNS cache. Especially since you've observed the effects of DNS record changes and cache clearing on name resolution and network troubleshooting.