DNS Resolution on Single NIC and Multiple IP’s


Who should read this : 

a) System Engineers

b) System Administrators

c) DNS Administrators

d) Active Directory Admins

e) Active Directory Technical Architects

 

Risk / Considerations: 

The changes below should be performed in the test environment and evaluate any dependent applications / hardcoded applications which are configured with the DNS and its behavior. The application behavior to be analyzed by the change includes, the DNS server response time, DNS Query forwarder and DNS Query failures.

 

Scenario: 

DNS name resolution is most critical aspect of any IT infrastructure, whether it is Microsoft DNS / UNIX the protocol behavior does not change. One such scenario is discussed below between IT Manager Mark and System Engineer Shaun.

 

IT Manager [Mark]: Good morning Shaun, on the Windows Server 2012 R2 member server with single NIC ( Network Interface Card ) installed and multiple IP Addresses configured, i would like to control DNS name resolution based on IP Address , is that possible ?

 

System Engineer [Shaun]: Hi Mark, can you elaborate your question please

 

IT Manager [Mark]: Sure, on the Windows Server 2012 R2 member server which is also acting as DNS server, i see that there are two IP Addresses configured on single NIC

IP Address 1 [Private] = 10.0.0.4

IP Address 2 [Public] = 4.13.24.45

Any Private DNS name resolution should be resolved by 10.0.0.4 and for any Public names ,the queries should be forwarded and resolved by 4.13.24.45 , how do we achieve this ?

 

System Engineer [Shaun]: This is highly unlikely to be achieved, Mark. The reason is with single NIC, there is no way to define the binding. The closest work around is to set the DNS server address order under the NIC properties

Note: This setting should be performed for Static IP Addresses and not controlled by Group Policy

Step1 : Logon to the Windows Server 2012 R2 using Administrator account / account which has privileges to make modifications to NIC

Step2: Start –> Run –> NCPA.cpl

Step3: Navigate to Network Adapter to be configured , right click the adapter –> Properties –> Internet Protocol Version 4 –> Properties

Step4: Navigate Advance TCP/IP Settings as shown below and add the DNS Server addresses IP Address under “DNS Server addresses, in                           order to use” section as shown below

image

 

Step 5: Click Ok and close all the windows of the Network interface

Step 6: Open the command prompt and run IPConfig / flushdns and IPConfig /registerdns

 

DNS Server priority is determined by the order. If the first server isn’t available to respond to a host name resolution request, the next DNS server in the list is accessed, and so on. To change the position of a server in the list box, select it and then click the up or down arrow button

 

 

 

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