One of my peers this week was looking for a script to help check global DNS resolution for particular records for both replication and geo-loadbalancing testing.
The record types and data he was looking for:
- A
- CNAME
- MX
- TXT (for SPF)
- TXT (for DMARC)
This is what I came up with, so maybe it can help someone else. 🙂
param (
[array]$Name,
$NameServers = @('8.8.8.8','4.2.2.2')
)
$global:ResolvedData = @()
foreach ($Server in $NameServers)
{
foreach ($obj in $Name)
{
$ARecordData = Resolve-DnsName -Name $obj -Type A -Server $Server -ea silentlycontinue
$CNAMERecordData = Resolve-DnsName -Name $obj -Type CNAME -Server $Server -ea silentlycontinue
$MXRecordData = Resolve-DnsName -Name $obj -Type MX -Server $Server -ea silentlycontinue
$TXTRecordData = Resolve-DnsName -Name $obj -Type TXT -Server $Server -ea silentlycontinue
$DMARCRecordData = Resolve-DnsName -Name selector1._domainkey.$obj -Type TXT -Server $Server -ea silentlycontinue
$RecordData = [ordered]@{
Hostname = $obj
Server = $Server
A = $ARecordData.IPAddress -join ","
CNAME = $CNAMERecordData.NameHost -join ","
MX = $MXRecordData.NameExchange -join ","
SPF = $TXTRecordData.Strings -match "v=spf1"
DMARC = $DMARCRecordData.Strings
}
}
$Record = New-Object PSobject -Property $RecordData
$global:ResolvedData += $Record
}
$ResolvedData
Copy/save to a .ps1, and then run with -Name (to specify the host or domain you want to check) and -Servers to specify which DNS servers you want to use for resolution.
Then, you can use the variable $ResolvedData to check and see what you’ve got, export to a CSV, filter, or whatever you so desire.