Powershell DHCP scope options extraction failure using Invoke-Command - powershell

Question

I'm trying to extract dhcp scope option info from a list of servers, the list obtained by querying AD for authorized dhcp servers in the domain. I'm using powershell's invoke-command to pass netsh dhcp server \\$servername scope $IP show optionvalue to a remote server. The $IP variable isn't passing the way the command wants to see it. It throws the The command needs a valid Scope IP Address. error.
I'm getting the scope ip address by first running netsh dhcp server \\$servername show scope and extracting the scope ip from that output, storing it in $IP.
I can type the IP in manually into the script and it returns the scope options but passing in the variable always returns the error. I've tested the command itself in a powershell console, both by manually typing in the IP and by creating a variable with the IP (as a string) and using it in the command, which works as well. There are no special characters, that i can tell, or white spaces when i store the IP in the script. I trim those out. I've also tried converting the string to an IP address using [IPAddress], to no avail.
Here is the code that gathers the scope info and then attempts to get the scope options:
foreach ($n in $name) {
$n
$showScopes = Invoke-command -computername $n -ScriptBlock {netsh dhcp server \\$n show scope}
$formatScopeInfo = $showScopes | ? {$_.Trim() -ne "" -and ($_.Contains("Disabled") -or $_.Contains("Active"))}
foreach ($en in $formatScopeInfo) {
$scopeIps = $en.Split("-")
$IP = [IPAddress]$scopeIps[0].Trim()
$IP.IPAddressToString
Invoke-Command -ComputerName $n -ScriptBlock {netsh dhcp server \\$n scope $IP.IPAddressToString show optionvalue}
}
The first foreach works and removes the lines that don't contain scope info. The second foreach partially works, it does strip out the IP. Initially i just stored it as a string, $IP = $scopeIps[0].Trim() but that wasn't working. I tried a number of things. I tried converting the octets to integers and joining them with ".", I tried to store the whole command as as a string and pass that into the Invoke-Command. Like so:
$command = "netsh dhcp server \\$n scope $IP show optionvalue"
Invoke-Command -ComputerName $n -ScriptBlock {$command}
The ultimate goal is to be able to extract any configured scope options, wherever they may be configured (server, reservation...etc). I fear I've gotten to that point where I'm so hyper-focused on what I think is the problem, that I may be missing something simple and/or crucial elsewhere. My opinion is that the command wants to see an actual IP address but my attempts to pass the variable that way have failed (and it works in the powershell console when saved as a string).
Fair disclosure, I'm still very much a novice and I was reluctant to post my code. I see so many on here with incredibly elegant solutions to things and, by comparison, my stuff seems extremely clunky. I've never had to post before as most times I can find/figure out where i've gone wrong. But I endeavor to learn and I have spent the better part of this weekend googling with no results. I have seen the script out there that works for pre 2012 servers but I really enjoy writing my own. I'm not looking to have anyone "do it for me", if you can point me down the appropriate rabbit hole; I'm happy to venture down it. Any suggestions on the code itself (appearance, better way of doing something...etc) are appreciated as well.
Apologies for the verbosity. I'm stuck and appreciate any help.

Answer 1

In your invoke-command you are not passing parameter,it should be like this:
$showScopes = Invoke-command -computername $n -ScriptBlock {
param($n)
netsh dhcp server \\$n show scope
} -argumentlist $n
and
Invoke-Command -ComputerName $n -ScriptBlock {
param($n,$IP)
netsh dhcp server \\$n scope $IP.IPAddressToString show optionvalue
} -argumentlist $n,$IP