DNS recorddata

This topic contains 10 replies, has 2 voices, and was last updated by  Don Jones 2 years, 5 months ago.

  • Author
  • #28033

    John Curtiss

    get-dnsserverresourcerecord -computername server -zonename zone.com -RRType A

    returns five columns. one of them is "name" and another is "Recorddata." name contains name, and recorddata contains the ip address.

    get-dnsserverresourcerecord -computername server -zonename zone.com -RRType A | -select name,Recorddata

    correctly returns the name in the first column, and "DNSServerResourceRecordA" on every row in the second column.

    how do I display just the name and ip address?

  • #28035

    Don Jones

    The default view that gets used when you just run Get-DnsServerResourceRecord does not display actual property names, and does some stuff to create a friendlier display than would otherwise happen by default.

    Once you use Select-Object, you dis-engage that default view.

    Start by piping the command to Get-Member so you can see the "real" property names. Or, use Select-Object * to see something similar. That'll help you figure it out. See also, https://powershell.org/kb/commands-default-output-can-lie/.

    Part of what can happen sometimes is that a property contains another complex object – like a DNSServerResourceRecordA object. You might need to use Select-Object's -ExpandProperty parameter to expand just that problematic object so you can see what IT looks like.

  • #28068

    John Curtiss

    thanks Don. I did not know about -expandproperty. get-member isn't really helpful, but I do see ipv4address when I use -expandproperty recorddata at the end of my original command.

    unfortunately I still don't know how to JUST show hostname and ipv4address in the output.

    ... | -select hostname -expandproperty recorddata

    gets me close, but there's an extra column called "PSComputername." the column is empty, but it's still there. is there a way to select just one of the expanded parts of recorddata?

  • #28070

    Don Jones

    It can be tricky. What you want is the combined output of two objects. Let's take these specific ones out of it for a second.

    Let's say I have Object A, and I want Property1, Property2, and Property3. There's also a Property4, and it's actually a sub-object, and I want Property4A from it. So that's four bits of output total.

    Get-ObjectA |
    Select-Object -Property Property1,Property2,Property3,@{
    e={$_.Property4 | Select-Object -ExpandProperty Property4A}

    That's the basic model.

    The first Select-Object is getting the "top level" properties from Object A. I'm then creating a "custom property" (also called a "calculated property"). In it, I set the output property name (n=) as Property4A, so that's what'll show in the output table. I then create an expression (e=) that defines what the custom property will contain.

    $_ represents whatever object Select-Object is working with, and so I take its Property4 – which is a sub-object, remember – and pipe it to another Select-Object, extracting the contents of the sub-object's Property4A, which is what I want.

    The resulting output is a single object with four properties, which PowerShell would by default display as a four-column table.

    This solves the "the thing I want to display includes sub-objects, and I only need a portion of the info those sub-objects contain." In your case, RecordData is Property4A... think you can take it from there?

  • #28085

    John Curtiss

    Get-DnsServerResourceRecord -ComputerName server -zonename zone.com -RRType A | select hostname,@{label='IP Address'; expression={$_.recorddata | select -expandproperty ipv4address}} | ft -AutoSize

    (after some research to figure out what your 'e' stood for 🙂 )

    thank you again. I've actually always wondered how to change the column names anyway, so. two birds, one thread.

  • #34136

    John Curtiss

    well. now. this is great and all for *outputting* data. but what if I want to query dns, and for records whose ip address is how do I use an expanded property in a where clause?

  • #34139

    Don Jones

    Ah, that's what -contains and -in are for.

    Assume I have an object $obj, which has a property prop. prop is actually a collection of [string] objects.

    ... | where { $obj.prop -contains "this" } | ...

    Because I'm providing a [string] "this", and that's what $obj.prop contains, it'll work.

  • #34146

    John Curtiss


    I must have missed something.

    Get-DnsServerResourceRecord -ComputerName DNSServer-ZoneName zone.com | ? {$_.recorddata -contains "10"}

    is not returning anything (every dns record in zone.com starts with 10)

  • #34147

    Don Jones

    So, that's the trick with -contains, It isn't a wildcard match. It's looking to see if $_.recorddata contains EXACTLY "10." Which, of course, it doesn't, right?

    So there's no way to do a wildcard match across a collection. You'll probably have to use a ForEach instead, and enumerate all the RecordData properties individually.

  • #34155

    John Curtiss

    my end goal is to feed a list of IPs into a foreach statement, and have the script output a list of FQDNs from DNS. but at this point i'm just testing with one IP that I know has a dns record.

    so if I do this:
    Get-DnsServerResourceRecord -ComputerName DNSServer -ZoneName zone.com -rrtype a | ? hostname -like host1 |select hostname, @{label='IP Address';expression={$_.recorddata |select -expandproperty ipv4address}}

    the output is hostname 'host1' and ip address so obviously there is an A record in my DNS named host1 with that ip address.

    but if I try to reverse the process to return 'host1' from the ip address, nothing is returned from the following:

    Get-DnsServerResourceRecord -ComputerName DNSServer -ZoneName zone.com -rrtype a | ? {$_.recorddata -contains ''}

  • #34156

    Don Jones

    You need a reverse lookup zone ;).

    So, do this:

    Get-DnsServerResourceRecord -ComputerName DNSServer -ZoneName zone.com -rrtype a | select -expand recorddata | get-member

    What's the TypeName?

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