Portfolio Project: Amechi Akpom

Exploring DNS Records and Cache:

A-Records, CNAME Records, and Local DNS Cache Management

In this DNS functionality demonstration, I examine DNS records and the local DNS cache through three hands-on exercises. Initially, I craft an A-record and watch its ripple effect on a client machine's DNS resolution. Then, I look at the local DNS cache, observing its role in DNS resolution. To round things up, I establish a CNAME record and note its influence on the client machine's DNS resolution. When finished, I have demonstrated DNS record management and cache as as indispensable tools for network management and diagnostic tasks.

Video Demonstration

Environments and Technologies Used

  • Microsoft Azure: A cloud computing platform by Microsoft that provides virtual machines and other resources.

  • Remote Desktop: A technology that allows users to access and control a computer or device from a remote location, as if they were physically present.

  • Internet Information Services (IIS): A web server software developed by Microsoft for hosting websites, applications, and other content on the internet or intranet.

  • Microsoft Active Directory: A directory service developed by Microsoft for Windows domain networks. It provides various network services such as authentication, authorization, and DNS services.

  • Domain Controller (DC): A server that responds to security authentication requests within a Windows Server domain. In this tutorial, we use DC-1 as the domain controller.

  • DNS (Domain Name System): A hierarchical and decentralized naming system for computers, services, or other resources connected to the internet or a private network. It translates human-readable domain names to IP addresses.

  • DNS Records: Data stored in DNS servers that contain information about domain names and their corresponding IP addresses. Examples of DNS records are A-records and CNAME records.

  • A-Record: An address record that maps a hostname to an IPv4 address.

  • CNAME Record: A canonical name record that maps one domain name (an alias) to another (the canonical name).

  • Command Prompt: A command-line interface available in most Windows operating systems. It allows users to execute commands and perform various tasks.

  • Ping: A utility that checks whether a particular host is reachable across an IP network. It measures the round-trip time for messages sent from the source host to a destination computer and back.

  • NSLookup: A network administration command-line tool available for many computer operating systems that helps obtain domain name or IP address mapping for any specific DNS record.

  • ipconfig: A command-line tool used on Windows operating systems to display the current network configuration, including IP addresses, subnet masks, and default gateways.

  • Hosts file: A plain text file in an operating system used to map hostnames to IP addresses. Its location in Windows is C:\windows\system32\drivers\etc\hosts.

Installation Steps

1. A-Record Exercise

  • Connect and log into your domain controller (DC-1) using your domain admin account (newroot.com\babs_admin)

  • Connect and log into your client machine (Client-1) using your domain admin account (newroot.com\babs_admin)

  • From Client-1, open the Command Prompt and execute ping www.amazon.com to ping www.amazon.com

  • Now, try to ping "supercomputer" and observe that it fails

  • Check the DNS cache using ipconfig /displaydns

  • Check the host file at C:\windows\system32\drivers\etc\hosts. You should not find any entry for "supercomputer"

  • Perform an NSLookup for "supercomputer" and observe that there is no DNS record (nslookup supercomputer)

  • Now, switch back to DC-1 and create a DNS A-record for "supercomputer" pointing to DC-1's private IP address

  • Return to Client-1 and try to ping "supercomputer" again. Observe that it works this time:

  • Perform an NSLookup for "supercomputer"

  • Check the DNS cache on Client-1 (ipconfig /displaydns or ipconfig /all)

2. Local DNS Cache Exercise

  • Go back to DC-1 and change the A-record for "supercomputer" to point to the IP address 8.8.8.8

  • Switch back to Client-1 and ping "supercomputer" again. Observe that it still pings the old address

  • Flush the DNS cache and observe that the cache is empty (ipconfig /flushdns)

  • Ping "supercomputer" again and observe that the new record's address is now showing up

3. CNAME Record Exercise

  • From Client-1, attempt to ping "search" and observe the results

  • Switch back to DC-1 and create a CNAME record that points the host "search" to "www.google.com"

  • Return to Client-1

  • Ping "search"

  • Flush the DNS cache and perform an NSLookup for "search" to observe the results of the CNAME record