ISE additional spacing and temperamental colur issues w/ function

Question

Hi All,
We've got some weird DNS issues where our DNS server doesn't seem to hold the latest addresses for our machines as provided by our DHCP server.
This is causing me a bit of a headache when trying to administer these machines remotely as I have to double check that the hostname points to the correct IP as otherwise I'll be making changes to a completely different machine than intended.
I thought a quick win would be a little PowerShell script. It seems to return the results as I'd expect, but there seem to be some inconsistencies with spacing when the script terminates, and issues with the colours that I've applied to some of the write-host
outputs.
Weirdly, the colour output of the write-host doesn't appear to be an issue if I pass the Hostname parameter whilst calling the function. Only seems to be when I prompt the user by the Read-Host.
The idea is:
1) Get the IP of a given hostname
2) Get the hostname of that given IP (to check that this matches the original hostname)
3) Act accordingly with the results of the above
I've tweaked the code so you can run with 'test' as the hostname
Running w/ PowerShell 4.
Set-PSDebug -Strict
Set-StrictMode -Version Latest
Clear-Host
Function Test-DNS
[CmdletBinding()]
Param
# Allow the user to specify the FQDN if it hasn't already been supplied
$Hostname = (Read-Host "Please specify Hostname"),
# Allow passing of the domain name.
$Domain = 'test.co.uk'
# Clear the screen after the read-host input
Clear-Host
# Throw an error if the hostname is not defined
if(!($Hostname))
Write-Host 'You have not specified a hostname. This script will now terminate.'
Write-Host ''
Break
# Define variables and assign null values
$IP_Response = @()
$IP_Count = $null
$Reverse_Lookup = $null
$Full_DNS_Name = $null
# Create the FQDN for a given hostname (if not already present)
if($Hostname -like "*$Domain")
$Full_DNS_Name = ($Hostname)
else
$Full_DNS_Name = ($Hostname + '.' + $Domain)
# Display the hostname
Write-Host $Hostname
Write-Host ''
# Try to grab the IP of a hostname and provide an error if this fails
Try
$IP_Response += '10.15.1.124' #([System.Net.Dns]::GetHostAddresses($Hostname) | Where {!($_.IsIPv6LinkLocal)}).IPAddressToString
$IP_Count = $IP_Response.Count
Catch [Exception]
Write-Host 'Error:' $_.Exception.Message -ForegroundColor Red
Write-Host ''
Break
# Check the number of results returned and warn the user if there are more than one
if($IP_Count -gt 1)
Write-Host 'WARNING:' $IP_Count 'addresses have been detected for this hostname.' -ForegroundColor Yellow
Write-Host ''
# Process each of the IPs that have been returned
ForEach($IP in $IP_Response)
Try
$Reverse_Lookup = 'test' #([System.Net.Dns]::GetHostByAddress($IP).HostName)
# If the reverse lookup matches the original hostname
if(($Reverse_Lookup -eq $Hostname) -or ($Reverse_Lookup -eq $Full_DNS_Name))
Write-Host 'Ping Response: ' $IP
Write-Host 'Reverse Lookup:' $Reverse_Lookup
Write-Host ''
Write-Host 'Success: Reverse DNS lookup was successful.' -ForegroundColor Green
Write-Host ''
# If the above is not true
else
Write-Host 'Ping Response: ' $IP
Write-Host 'Reverse Lookup:' $Reverse_Lookup
Write-Host ''
Write-Host 'Error: Reverse DNS lookup did not match the provided hostname.' -ForegroundColor Red
Write-Host ''
Catch [Exception]
Write-Host $IP
Write-Host 'Error:' $_.Exception.Message -ForegroundColor Red
Write-Host ''
Test-DNS
This is what happens after a few runs (usually when I've terminated the script part way through), without passing the Hostname parameter:
http://s16.postimg.org/sb2lehqdx/Output_1.png
(It also applies to some of the other write-host outputs), including error messages and the dbg messages that appear when I set breakpoints)
Now, onto the spacing issue...
If I continue to refresh the screen or rerun the script, it will sometimes randomly put two blank spaces before terminating. I've only specified one. I can't understand why this happens
This is how it appears when there are two spaces
http://s23.postimg.org/bgtg0hx5n/Output_3.png
I have just noticed that when it does display correctly (1 space), the first two characters of 'Success' are white, while the rest remain green.
Can anybody shed any light on this? It's driving me round the bend!
Cheers.

Answer 1

I've changed the function to instead output a custom PSObject with the results, which are then processed by another script. I believe this is a much better approach and I don't have any issues as of yet with the spaces / colouring.
For anyone interested, this is the end result:
Function Test-DNS
[CmdletBinding()]
Param
# Allow the user to specify the FQDN if it hasn't already been supplied
[Parameter(Mandatory=$true)]
$Hostname = $null,
# Allow passing of the domain name.
$Domain = 'domain.co.uk'
# Throw an error if the hostname is not defined
if(!($Hostname))
Throw 'You must specify a Hostname'
# Null variables
$Forward_Host_Address = @()
$Forward_Host_Address_Count = $null
$FQDN = $null
$Reverse_Hostname = $null
$Result_Output = @()
$Match = $null
# Convert the Hostname to upper case and remove the domain from the hostname input (if included)
$Hostname = $Hostname.ToUpper() -replace ".$Domain"
# Create a variable for the FQDN of the specified host
$FQDN = "$Hostname.$Domain"
# Try to get the IP of the given hostname (forward lookup)
Try
$Forward_Host_Address += ([System.Net.Dns]::GetHostEntry($Hostname) | Select -ExpandProperty AddressList | Where {!($_.IsIPv6LinkLocal)}).IPAddressToString
$Forward_Host_Address_Count = $Forward_Host_Address.Count
Catch [Exception]
Throw "A DNS record for $Hostname Could not be found"
# Try to get the host name of the received IP(s) (reverse lookup)
ForEach($IP_Response in $Forward_Host_Address)
Try
$Reverse_Hostname = ([System.Net.Dns]::GetHostEntry($IP_Response)).HostName
Catch [Exception]
Throw $_.Exception.Message
if(($Reverse_Hostname -eq $Hostname) -or ($Reverse_Hostname -eq $FQDN))
$Match = $true
$Result_Output += New-Object PSObject -Property ([ordered]@{
Hostname = $Hostname
IP_Response = $IP_Response
Reverse_Hostname = $Reverse_Hostname
Match = $Match
else
$Match = $false
$Result_Output += New-Object PSObject -Property ([ordered]@{
Hostname = $Hostname
IP_Response = $IP_Response
Reverse_Hostname = $Reverse_Hostname
Match = $Match
Return $Result_Output
Clear-Host
Import-Module 'Test-DNS.ps1'
$Hostname = $null
$IP_Response = $null
$Reverse_Hostname = $null
$Reverse_Match = $null
$Hostname = Read-Host 'Hostname'
Write-Output ''
$DNS_Check = Test-DNS $Hostname
$IP_Response = $DNS_Check.IP_Response
$Reverse_Hostname = $DNS_Check.Reverse_Hostname
$Reverse_Match = $DNS_Check.Match
Write-Output "Address Response: $IP_Response"
Write-Output "Reverse Hostname: $Reverse_Hostname"
Write-Output ''
if($Reverse_Match)
Write-Output '[OK] The reverse lookup matched the original request.'
else
Write-Output '[ERROR] The reverse lookup did not match the original request.'
(Powershell 4)