Get DNS CNAMES recursively for specified Servers

getCNAME.ps1

param (
    [Parameter(Mandatory = $true)]
    [string]$dnsServer,
    [Parameter(Mandatory = $true)]
    [string[]]$lookupZones,
    [Parameter(Mandatory = $true)]
    [string[]]$specificServerNames
)

function Get-CNameRecords {
    param (
        [string]$dnsServer,
        [string[]]$lookupZones,
        [string[]]$specificServerNames
    )

    $results = @()

    foreach ($zone in $lookupZones) {
        try {
            $cnames = Get-DnsServerResourceRecord -ZoneName $zone -ComputerName $dnsServer -RRType "CNAME" -ErrorAction Stop
            foreach ($cname in $cnames) {
                $target = $cname.RecordData.HostNameAlias
                foreach ($serverName in $specificServerNames) {
                    if ($target -like "*$serverName*") {
                        $additionalCNames = Find-CNameChain -dnsServer $dnsServer -zone $zone -target $cname.HostName
                        $results += [pscustomobject]@{
                            Zone = $zone
                            CName = $cname.HostName
                            Target = $target
                            AdditionalCNames = $additionalCNames -join ', '
                        }
                    }
                }
            }
        } catch {
            Write-Warning "Failed to query DNS records for zone $zone : $_"
        }
    }

    return $results
}

function Find-CNameChain {
    param (
        [string]$dnsServer,
        [string]$zone,
        [string]$target
    )

    $additionalCNames = @()
    try {
        $cnameRecords = Get-DnsServerResourceRecord -ZoneName $zone -ComputerName $dnsServer -RRType "CNAME" -ErrorAction Stop
        foreach ($record in $cnameRecords) {
            if ($record.RecordData.HostNameAlias -like "*$target*") {
                $additionalCNames += $record.HostName
            }
        }
    } catch {
        Write-Warning "Failed to find additional CNAME chain for $target in $zone : $_"
    }

    return $additionalCNames
}

# Execute the function and handle results
$results = Get-CNameRecords -dnsServer $dnsServer -lookupZones $lookupZones -specificServerNames $specificServerNames
if ($results.Count -gt 0) {
    $results | Export-Csv -Path "CNameResults.csv" -NoTypeInformation
    Write-Host "Results exported to CNameResults.csv"
} else {
    Write-Host "No matching CNAME records found."
}