DNS

Get Primary, Secondary, Tertiary DNS values and more from Multiple Servers

Came across a unique request to get primary, secondary, and tertiary DNS values for multiple computers/servers across the domain. I started writing the script and got what I wanted.

Now this started off as just to query for DNS Server information, but then I thought to add other pieces to get myself a good Network Inventory of all the servers in the environment.

I am utilizing the Win32_NetworkAdapterConfiguration WMI Class to get the required information.

You can modify the script below to suit your needs. The complete list of settings that can be captured:

Since the scripts are querying for information it is best if it runs from a DC or a privileged server with an account that has privileged access.

To get the results you need the following two scripts:

Get-NetworkInfo.ps1:

I needed to get all the network information for all the domain controllers in the domain. So the following code retrieves it for me. This came really handy in viewing all the DNS settings setup on all the DCs and correcting them if needed.

Get-Remote-NetworkInfo.ps1

This will get the information and export to an excel file that you can have handy for reference or auditing. Hope this helps!

Convert a Dynamic IP to Static

Working on a project where on some servers the DHCP assigned addresses needs to be converted to static. Since there is always more than one…I needed to script it.

Here is a quick way to do it via PowerShell.

Hope this helps!

NSLookup still showing IP of demoted Domain Controller

So had an interesting issue today where a Domain Controller (DC) was demoted yet the IP of the demoted DC was still showing up when running nslookup internaldomain.local

Demoted DC: MWDC04 / IP: 10.14.111.111

I had done the metadata cleanup and tried many suggestions when googling the subject. To my surprise none of the solutions I found worked.

I had removed the IP address from the Primary DNS Server and saw entries for:

(same as parent folder) Host(A)  10.14.111.111
(same as parent folder) NameServer (NS)  10.14.111.111

I also looked under internaldomain.local > _msdcs and deleted entries from there.

After clearing the cache and waiting for replication, did a nslookup again and the IP was still there.

Well, there are some good and bad things about Microsoft DNS.

The BAD:

You cannot search DNS values in DNS Management. You are limited to searching just the names.

THE GOOD:

All DNS entries are stored in a flat file on the DNS Server “C:\WINDOWS\system32\dns\internaldomain.local.dns” (The default location). JACKPOT!

I opened it up in Notepad++, did a search for IP and DNS name of the demoted server(MWDC04-10.14.111.111) and started deleting matched entries. I was so surprised to find entries that were deeply buried under “domaindnszones” & “forestdnszones” and a few other subzones.

Cleared the cache again and waited for replication. Once replication completed I tried nslookup internaldomain.local and this time it didn’t list the demoted DC anymore.

I hope this saves others time, because finding a record in DNS might be like searching for a needle in a haystack!

Speed up Active Directory & DNS replication between Sites

Using the standard GUI Microsoft Management Consoles to make the change to speed up Active Directory replication is not possible. The best result of using administrator consoles will be to increase domain replication between domain controllers to 15 minutes. These large time values were instituted into Active Directory at version 1 because inter-site connections during that era of computing and networking were much lower in bandwidth with the most common being frame-relay or 56k circuits. Since then, inter-site connections and the Internet speeds have increased tremendously so faster domain controller replication is possible even over wan links.

Fast Intersite Replication Interval – Speed up DC Replication, Updates are in Seconds

To enabled faster Intersite Replication, to nearly the speed of intra-site or LAN replication, use ADSI Edit.
Start ADSI edit and go to
Configuration > then Sites > Inter Site Transports > IP.
Note this setting cannot be enabled for SMTP InterSite links.
Unless it has been renamed, right click on  the default Intersite link and choose properties. Then scroll down to the options line. Double-click and change the value to 1 if it has a value .
 <not set> is the default unless this option has been previously modified.  Once changed to 1, click OK twice to save and close the properties window.
Force a replication using Sites and Services so this setting get pushed/pulled to the other domain controllers.
Test by creating a couple of test accounts in AD.
Check your other domain controller or controllers for the new account. You will see it appear in seconds.

Resolve IP Addresses from List of Host Names

If you have a list of hostnames/servers that you need IP addresses for its cumbersome to ping each server and get the ip address.

PowerShell to the rescue!

To do this we need a file called Server.txt with each server’s hostname on each line. I am storing the file in D:\Data\Servers.txt.

Once we run the script below it resolves the ip via DNS and stores to another file called D:\Data\Addresses.txt.

All the IP addresses are getting pulled from their DNS value. 

DNS broken after Windows Update KB3145126

I noticed the DNS broke on my servers after Windows Update.

The problem was KB3145126. Read more about it here.

After a quick removal and reboot, DNS was operational again.

To remove/uninstall KB3145126, open powershell and run the following:

Hope this helps.