Strange DNS record duplication with Powershell? - powershell

Question

While recently working with the native Powershell DNS commandlets, specifically Get-DNSServerResourceRecord, I noticed something strange that does not make sense to me.
When I look into my zone using native DNS tools, LDAP query tools, or even ADSIedit, I see only a single DNS object representing a given hostname.
However, when I do the same with Powershell, I instead get two objects for a given host, one for the NETBIOS name, and the other for the FQDN. All other attributes are the same, including the IP.
For example, if I had a computer named computer1: This is what I see.
PS C:\> Get-DnsServerResourceRecord -ZoneName 'mydomain.local' -RRType A -ComputerName 'DNSServer1' | Where-Object {$_.hostname -like "Computer1*"} | fl *
DistinguishedName : DC=computer1.mydomain.local,DC=mydomain.local,cn=MicrosoftDNS,DC=DomainDnsZones,DC=mydomain,DC=local
HostName : COMPUTER1.mydomain.local
RecordClass : IN
RecordData : DnsServerResourceRecordA
RecordType : A
Timestamp :
TimeToLive : 01:00:00
Type : 1
PSComputerName :
CimClass : root/Microsoft/Windows/DNS:DnsServerResourceRecord
CimInstanceProperties : {DistinguishedName, HostName, RecordClass, RecordData...}
CimSystemProperties : Microsoft.Management.Infrastructure.CimSystemProperties
DistinguishedName : DC=computer1,DC=mydomain.local,cn=MicrosoftDNS,DC=DomainDnsZones,dc=mydomain,dc=local
HostName : COMPUTER1
RecordClass : IN
RecordData : DnsServerResourceRecordA
RecordType : A
Timestamp :
TimeToLive : 01:00:00
Type : 1
PSComputerName :
CimClass : root/Microsoft/Windows/DNS:DnsServerResourceRecord
CimInstanceProperties : {DistinguishedName, HostName, RecordClass, RecordData...}
CimSystemProperties : Microsoft.Management.Infrastructure.CimSystemProperties
I'm so confused at why Powershell is showing this and where it's actually pulling it from. I cannot locate those FQDN objects using native LDAP tools, even ADFind.
Is this some weird artifact/bug of the Powershell DNS cmdlets? Or does DNS records store dual entries for a given host, but only display one using native tools?
Neither make sense to me, as I would not expect a cmdlet to just make up DN values on the fly, and this doesn't occur for all host records.The latter does not seem possible as this is not occurring for all records in the zone. I have about 100 more records without the fqdn than with (10926 vs 10824).
EDIT If it helps, here is an ADFind query for the same object (and wildcard).
C:\temp>adfind -h dnsserver1 -domaindns -f "(&(name=computer1*))" name
AdFind V01.57.00cpp Joe Richards (support#joeware.net) November 2021
Using server: dnsserver1.mydomain.local:389
Directory: Windows Server 2016
Base DN: DC=DomainDnsZones,DC=ad,DC=ewsad,DC=net
dn:DC=computer1,DC=mydomain.local,CN=MicrosoftDNS,DC=DomainDnsZones,DC=mydomain,DC=local
>name: computer1
1 Objects returned

Answer 1

I can confirm this behavior.
In powershell, this returns 2 results for many of the computers (maybe all, I didn't check)
Get-DnsServerResourceRecord -ZoneName 'domain.com' -RRType A -ComputerName dnserver1 | where hostname -like Computer1*
DistinguishedName : DC=Computer1.domain.com,DC=domain.com,cn=MicrosoftDNS,DC=DomainDnsZones,DC=domain,DC=com
HostName : Computer1.domain.com
RecordClass : IN
RecordData : DnsServerResourceRecordA
RecordType : A
Timestamp : 12/8/2022 9:00:00 AM
TimeToLive : 00:20:00
Type : 1
PSComputerName :
CimClass : root/Microsoft/Windows/DNS:DnsServerResourceRecord
CimInstanceProperties : {DistinguishedName, HostName, RecordClass, RecordData...}
CimSystemProperties : Microsoft.Management.Infrastructure.CimSystemProperties
DistinguishedName : DC=Computer1,DC=domain.com,cn=MicrosoftDNS,DC=DomainDnsZones,DC=domain,DC=com
HostName : Computer1
RecordClass : IN
RecordData : DnsServerResourceRecordA
RecordType : A
Timestamp : 12/8/2022 9:00:00 AM
TimeToLive : 00:20:00
Type : 1
PSComputerName :
CimClass : root/Microsoft/Windows/DNS:DnsServerResourceRecord
CimInstanceProperties : {DistinguishedName, HostName, RecordClass, RecordData...}
CimSystemProperties : Microsoft.Management.Infrastructure.CimSystemProperties
But a dsquery results in one record.
dsquery computer -name computer1* -s dnsserver1
"CN=Computer1,OU=Computers,DC=domain,DC=com"
You can confirm only one of these is a real AD object.
$recordlist = Get-DnsServerResourceRecord -ZoneName 'domain.com' -RRType A -ComputerName dnserver1 | where hostname -like Computer1*
foreach($record in $recordlist){
Write-Host "Checking DN $($record.DistinguishedName)" -ForegroundColor Cyan
$found = $record.DistinguishedName |
Get-ADObject -ErrorAction SilentlyContinue
if($found){
Write-Host "Record found in AD" -ForegroundColor Green
}
else{
Write-Host "Record not in AD" -ForegroundColor DarkGray
}
}
So I must conclude thus far the evidence does indicate the Get-DnsServerResourceRecord is adding a duplicated record with the FQDN as well. Hopefully someone can find or knows why it was implemented in this manner.