functions/Resolve-DbaNetworkName.ps1

Function Resolve-DbaNetworkName
{
  <#
      .SYNOPSIS
      Returns information about the network connection of the target computer including NetBIOS name, IP Address, domain name and fully qualified domain name (FQDN).
 
      .DESCRIPTION
      Retrieves the IPAddress, ComputerName from one computer.
      The object can be used to take action against its name or IPAddress.
 
      First ICMP is used to test the connection, and get the connected IPAddress.
 
      If your local Powershell version is not higher than 2, WMI is tried to get the computername.
      If not, CIM is used, first via WinRM, and if not successful, via DCOM.
 
      .PARAMETER ComputerName
      The Server that you're connecting to.
      This can be the name of a computer, a SMO object, an IP address or a SQL Instance.
 
      .PARAMETER Credential
      Credential object used to connect to the SQL Server as a different user
 
      .PARAMETER Turbo
      Resolves without accessing the serer itself. Faster but may be less accurate.
 
      .NOTES
      Author: Klaas Vandenberghe ( @PowerDBAKlaas )
 
      dbatools PowerShell module (https://dbatools.io)
      Copyright (C) 2016 Chrissy LeMaire
      This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
      This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
      You should have received a copy of the GNU General Public License along with this program. If not, see http://www.gnu.org/licenses/.
 
      .LINK
      https://dbatools.io/Resolve-DbaNetworkName
 
      .EXAMPLE
      Resolve-DbaNetworkName -ComputerName ServerA
 
      Returns a custom object displaying InputName, ComputerName, IPAddress, DNSHostName, Domain, FQDN for ServerA
     
      .EXAMPLE
      Resolve-DbaNetworkName -SqlServer sql2016\sqlexpress
 
      Returns a custom object displaying InputName, ComputerName, IPAddress, DNSHostName, Domain, FQDN for the SQL instance sql2016\sqlexpress
     
      .EXAMPLE
      Resolve-DbaNetworkName -SqlServer sql2016\sqlexpress, sql2014
 
      Returns a custom object displaying InputName, ComputerName, IPAddress, DNSHostName, Domain, FQDN for the SQL instance sql2016\sqlexpress and sql2014
 
      Get-SqlRegisteredServerName -SqlServer sql2014 | Resolve-DbaNetworkName
     
      Returns a custom object displaying InputName, ComputerName, IPAddress, DNSHostName, Domain, FQDN for all SQL Servers returned by Get-SqlRegisteredServerName
  #>

    [CmdletBinding()]
    param (
        [parameter(ValueFromPipeline)]
        [Alias('cn', 'host', 'ServerInstance', 'Server', 'SqlServer')]
        [object[]]$ComputerName = $env:COMPUTERNAME,
    [PSCredential] [System.Management.Automation.CredentialAttribute()]$Credential,
        [Alias('FastParrot')]
        [switch]$Turbo
    )
    BEGIN
    {
        $functionName = (Get-PSCallstack)[0].Command
    }
    PROCESS
    {
        foreach ($Computer in $ComputerName)
        {
            $conn = $ipaddress = $CIMsession = $null
            
            if ($Computer.GetType() -eq [Microsoft.SqlServer.Management.Smo.Server])
            {
                $Computer = $Computer.NetName
            }
            
            $OGComputer = $Computer
            
            if ($Computer -eq 'localhost' -or $Computer -eq '.')
            {
                $Computer = $env:COMPUTERNAME
            }
            
            $Computer = $Computer.Split('\\')[0]
            $Computer = ($Computer -Split ('\:'))[0]
            $Computer = ($Computer.Split('\,'))[0]
            
            if ($Turbo)
            {
                try
                {
                    Write-Verbose "$functionName - Resolving $Computer using .NET.Dns GetHostEntry"
                    $ipaddress = ([System.Net.Dns]::GetHostEntry($Computer)).AddressList[0].IPAddressToString
                    Write-Verbose "$functionName - Resolving $ipaddress using .NET.Dns GetHostByAddress"
                    $fqdn = [System.Net.Dns]::GetHostByAddress($ipaddress).HostName
                }
                catch
                {
                    try
                    {
                        Write-Verbose "$functionName - Resolving $Computer and IP using .NET.Dns GetHostEntry"
                        $resolved = [System.Net.Dns]::GetHostEntry($Computer)
                        $ipaddress = $resolved.AddressList[0].IPAddressToString
                        $fqdn = $resolved.HostName
                    }
                    catch
                    {
                        Write-Warning "$functionName - DNS name not found"
                        continue
                    }
                }
                
                if ($fqdn -notmatch "\.")
                {
                    $dnsdomain = $env:USERDNSDOMAIN.ToLower()
                    $fqdn = "$fqdn.$dnsdomain"
                }
                
                $hostname = $fqdn.Split(".")[0]
                
                [PSCustomObject]@{
                    InputName = $OGComputer
                    ComputerName = $hostname.ToUpper()
                    IPAddress = $ipaddress
                    DNSHostname = $hostname
                    Domain = $fqdn.Replace("$hostname.", "")
                    DNSHostEntry = $fqdn
                    FQDN = $fqdn
                }
                return
            }
            
            Write-Verbose "$functionName - Connecting to $Computer"
            
            try
            {
                $ipaddress = ((Test-Connection -ComputerName $Computer -Count 1 -ErrorAction Stop).Ipv4Address).IPAddressToString
            }
            catch
            {
                try
                {
                    $ipaddress = ((Test-Connection -ComputerName "$Computer.$env:USERDNSDOMAIN" -Count 1 -ErrorAction SilentlyContinue).Ipv4Address).IPAddressToString
                    $Computer = "$Computer.$env:USERDNSDOMAIN"
                }
                catch
                {
                    $Computer = $OGComputer
                    $ipaddress = ([System.Net.Dns]::GetHostEntry($Computer)).AddressList[0].IPAddressToString
                }
            }
            
            if ($ipaddress)
            {
                Write-Verbose "$functionName - IP Address from $Computer is $ipaddress"
            }
            else
            {
                Write-Verbose "$functionName - No IP Address returned from $Computer"
                Write-Verbose "$functionName - Using .NET.Dns to resolve IP Address"
                return (Resolve-DbaNetworkName -ComputerName $Computer -Turbo)
            }
            
            if ($host.Version.Major -gt 2)
            {
                Write-Verbose "$functionName - Your PowerShell Version is $($host.Version.Major)"
                try
                {
                    Write-Verbose "$functionName - Getting computer information from $Computer via CIM (WSMan)"
                    if ($Credential)
                    {
                        $CIMsession = New-CimSession -ComputerName $Computer -ErrorAction Stop -Credential $Credential
                        $conn = Get-CimInstance -Query "Select * FROM Win32_computersystem" -CimSession $CIMsession -ErrorAction Stop
                    }
                    else
                    {
                        $conn = Get-CimInstance -Query "Select * FROM Win32_computersystem" -ComputerName $Computer -ErrorAction Stop
                    }
                }
                catch
                {
                    Write-Verbose "$functionName - No WSMan connection to $Computer"
                }
                if (!$conn)
                {
                    try
                    {
                        Write-Verbose "$functionName - Getting computer information from $Computer via CIM (DCOM)"
                        $sessionoption = New-CimSessionOption -Protocol DCOM
                        if ($Credential)
                        {
                            $CIMsession = New-CimSession -ComputerName $Computer -SessionOption $sessionoption -ErrorAction Stop -Credential $Credential
                            
                        }
                        else
                        {
                            $CIMsession = New-CimSession -ComputerName $Computer -SessionOption $sessionoption -ErrorAction Stop
                        }
                        
                        $conn = Get-CimInstance -Query "Select * FROM Win32_computersystem" -CimSession $CIMsession -ErrorAction Stop
                    }
                    catch
                    {
                        Write-Warning "$functionName - No DCOM connection for CIM to $Computer"
                    }
                }
                
                if (!$conn)
                {
                    Write-Verbose "$functionName - No CIM from $Computer. Getting HostName via .NET.Dns"
                    try
                    {
                        $fqdn = ([System.Net.Dns]::GetHostEntry($Computer)).HostName
                        $hostname = $fqdn.Split(".")[0]
                        
                        $conn = [PSCustomObject]@{
                            Name = $Computer
                            DNSHostname = $hostname
                            Domain = $fqdn.Replace("$hostname.", "")
                        }
                    }
                    catch
                    {
                        Write-Warning "$functionName - No .NET.Dns information from $Computer"
                        continue
                    }
                }
            }
            
            
            try
            {
                Write-Verbose "$functionName - Resolving $($conn.DNSHostname) using .NET.Dns GetHostEntry"
                $hostentry = ([System.Net.Dns]::GetHostEntry($conn.DNSHostname)).HostName
            }
            catch
            {
                Write-Warning "$functionName - .NET.Dns GetHostEntry failed for $($conn.DNSHostname)"
            }
            
            $fqdn = "$($conn.DNSHostname).$($conn.Domain)"
            if ($fqdn -eq ".")
            {
                Write-Verbose "$functionName - No full FQDN found. Setting to null"
                $fqdn = $null
            }
            
            [PSCustomObject]@{
                InputName = $OGComputer
                ComputerName = $conn.Name
                IPAddress = $ipaddress
                DNSHostName = $conn.DNSHostname
                Domain = $conn.Domain
                DNSHostEntry = $hostentry
                FQDN = $fqdn
            }
        }
    }
}