How to avoid unnecessary output from [System.Net.Dns]::GetHostAddresses("$server_name")

Question

$inventory = Import-Csv "E:\MonitoringScripts\HealthCheck\PatStat_Pshell\inventory.csv"
foreach ($line in $inventory) {
    $server_name = $($line.servername)
    $port_number = $($line.port)
    $resolved_true = [System.Net.Dns]::GetHostAddresses("$server_name") 
    #Write-Host $resolved_true
    if ($resolved_true) {
        #Write-Host $server_name
        Write-Host 'the host is resolving'
    } else {
        Write-Host 'Not found in DNS'
    }
}

In the above code, how do I avoid the below content to appear in the command promt when there is a host in the inventory file which is not resolving the dns?

Exception calling "GetHostAddresses" with "1" argument(s): "No such host is
known"
At E:\MonitoringScripts\HealthCheck\PatStat_Pshell\patrol.ps1:9 char:2
+     $resolved_true = [System.Net.Dns]::GetHostAddresses("$server_name")
+     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (:) [], MethodInvocationException
    + FullyQualifiedErrorId : SocketException

Not found in DNS
the host is resolving

I just want to see:

Not found in DNS

or

the host is resolving

First you should remove the quotes around the variable $server_name. How to you run this code? — Olaf
– Olaf, Commented Feb 25, 2019 at 18:22
PS E:\MonitoringScripts\HealthCheck\PatStat_Pshell> .\patrol.ps1 Exception calling "GetHostAddresses" with "1" argument(s): "No such host is known" At E:\MonitoringScripts\HealthCheck\PatStat_Pshell\patrol.ps1:9 char:2 + $resolved_true = [System.Net.Dns]::GetHostAddresses("$server_name") | foreach { ... + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~ + CategoryInfo : NotSpecified: (:) [], MethodInvocationException + FullyQualifiedErrorId : SocketException Not found in DNS the host is resolving — kaushik km
– kaushik km, Commented Feb 25, 2019 at 18:28
Its running fine event with out removing the double quots. but as suggested i will go ahead and remove it. — kaushik km
– kaushik km, Commented Feb 25, 2019 at 18:29
take a look at the 3rd answer here ... Powershell: How can I stop errors from being displayed in a script? - Stack Overflow — stackoverflow.com/questions/8388650/… — Lee_Dailey
– Lee_Dailey, Commented Feb 25, 2019 at 18:31
You might use if (Test-Connection -ComputerName $server_name) { — lit
– lit, Commented Feb 25, 2019 at 18:32

Ansgar Wiechers · Accepted Answer · 2019-02-25 18:51:34Z

1

Catch the exception:

try {
    [Net.Dns]::GetHostAddresses($server_name)
    Write-Host 'the host is resolving'
} catch {
    Write-Host 'Not found in DNS'
}

answered Feb 25, 2019 at 18:51

Ansgar Wiechers

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6 Comments

kaushik km Over a year ago

Exception calling "GetHostAddresses" with "1" argument(s): "No such host is known" At E:\MonitoringScripts\HealthCheck\PatStat_Pshell\patrol.ps1:9 char:2 + $resolved_true = [System.Net.Dns]::GetHostAddresses($server_name) + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + CategoryInfo : NotSpecified: (:) [], ParentContainsErrorRecordE xception + FullyQualifiedErrorId : SocketException

kaushik km Over a year ago

yes @Ansgar Wiechers, i am trying to post the code which i tried.. unable to post it with proper indentation

Ansgar Wiechers Over a year ago

Just click on the "edit" link right below your question and add your modified code. BTW, what output does $PSVersionTable give you? Include that output as well.

kaushik km Over a year ago

here it was executing the command and giving the output of [Net.Dns]::GetHostAddresses($server_name) which is not required

kaushik km Over a year ago

PSVersion 3.0 WSManStackVersion 3.0 SerializationVersion 1.1.0.1 CLRVersion 4.0.30319.36470 BuildVersion 6.2.9200.22198

|

JosefZ · Accepted Answer · 2019-02-25 18:53:03Z

0

Read About Try Catch Finally:

Use Try, Catch, and Finally blocks to respond to or handle terminating errors in scripts.

You can apply it as follows:

try {
    $resolved_true = [System.Net.Dns]::GetHostAddresses($server_name)
} catch {
    $resolved_true = $null
}

answered Feb 25, 2019 at 18:53

JosefZ

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Comments

lit · Accepted Answer · 2019-02-25 18:51:58Z

0

Test-Connection to see if the host exists first. Of course, the host existing is not exactly the same thing as finding it in DNS.

$inventory = import-csv “E:\MonitoringScripts\HealthCheck\PatStat_Pshell\inventory.csv”
ForEach ($line in $inventory)
{
    $server_name = $($line.servername)
    $port_number = $($line.port)
    $resolved_true = $null
    if (Test-Connection -ComputerName $server_name -ErrorAction SilentlyContinue) {
        $resolved_true = [System.Net.Dns]::GetHostAddresses("$server_name")
    }
    #Write-host $resolved_true
    if($resolved_true) {
        #write-host $server_name
        Write-Host 'the host is resolving'
    } else {
        Write-Host 'Not found in DNS'
    }
}

edited Feb 25, 2019 at 18:51

answered Feb 25, 2019 at 18:45

lit

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5 Comments

kaushik km Over a year ago

Test-connection started to throw error, as it was not able to find the host. i just do not want the error to be thrown, let it go to the else condition

kaushik km Over a year ago

PS E:\MonitoringScripts\HealthCheck\PatStat_Pshell> .\patrol2.ps1 Test-Connection : Testing connection to computer 'vlhebsadv06abc' failed: The requested name is valid, but no data of the requested type was found At E:\MonitoringScripts\HealthCheck\PatStat_Pshell\patrol2.ps1:7 char:9 + if (Test-Connection $server_name) { + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + CategoryInfo : ResourceUnavailable: (vlhebsadv06abc:String) [Te st-Connection], PingException + FullyQualifiedErrorId : TestConnectionException,Microsoft.PowerShell.Com mands.TestConnectionCommnd

kaushik km Over a year ago

how to use -ErrorAction ?

kaushik km Over a year ago

wow this is what i was looking for. Thank you. not sure why.. but it is taking very long time to execute. any idea ? or how to improve ? i am just running this for two hosts.. and it took 4-5 seconds i would want to run this on more than 2K hosts

lit Over a year ago

@kaushikkm - Actually, the try/catch exception handling approach would be more direct. I am surprised it did not work for you.

kaushik km · Accepted Answer · 2019-02-25 19:32:33Z

0

$inventory = import-csv “E:\MonitoringScripts\HealthCheck\PatStat_Pshell\inventory.csv”
ForEach ($line in $inventory)
{
    $server_name = $($line.servername)
    $port_number = $($line.port)
    $resolved_true = $null
    try {
    $resolved_true = [System.Net.Dns]::GetHostAddresses($server_name) 
    } catch {
    $resolved_true = $null
    }
    #Write-host $resolved_true
    if($resolved_true) {
        #write-host $server_name
        Write-Host 'the host is resolving'
    } else {
        Write-Host 'Not found in DNS'
    }
}

This worked for me, Thank you so much all for the help. I will have to mark @JosefZ Answer, But really thank you all.

answered Feb 25, 2019 at 19:32

kaushik km

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