IPAddress.TryParse Method

IPAddress.TryParse uses inet_addr under the hood to parse an IPv4 address. This makes the following rules valid:

1) Each part of the address can be either specified in decimal, octal or hexadecimal notation. A leading zero will indicate an octal number, a "0x" prefix will indicate an hexadecimal one. The following strings will all parse to the same address:

"16.16.16.16" // decimal
"020.020.020.020" // octal
"0x10.0x10.0x10.0x10" // hexadecimal
"16.020.0x10.16" // mixed base

2) Compatibility with Berkley software:

When a three-part address is specified, the last part is interpreted as a 16-bit quantity and placed in the right-most 2 bytes of the network address.

Example: "12.12.258" is valid and maps to 12.12.1.2

When a two-part address is specified, the last part is interpreted as a 24-bit quantity and placed in the right-most 3 bytes of the network address.

Example: "12.258" is valid and maps to 12.0.1.2

For further information, read the MSDN article on inet_addr.

<#
.SYNOPSIS
    Demonstrates use of the GetHostEntry method of System.Net.DNS Class
.DESCRIPTION
    This script is a an MSDN sample, using PowerShell. This script
    uses the IP address of the host to find.
.NOTES
    File Name  : Get-HostEntry2.ps1
    Author     : Thomas Lee - tfl@psp.co.uk
    Requires   : PowerShell V2
.LINK
    Sample posted to:
        http://pshscripts.blogspot.com/
    Original MSDN sample at:
        http://msdn.microsoft.com/en-us/library/ms143997.aspx
.EXAMPLE
    PSH [C:\foo]: .\Get-HostEntry2.ps1 10.10.1.117
    Host Name    : cookham11.cookham.net
    Alias        :
    Address      : 10.10.1.117
.PARAM HostName
    The name of the host to search for - the default is "127.0.0.1"
#>

param (
[string] $HostAddress = "127.0.0.1"
)

###
# Start of Script
###

# Convert $hostaddres to IPaddress class. 

# Create one for next call
$HostIp = [System.Net.IPAddress]::Parse("127.0.0.1")
if (! ([system.Net.IPAddress]::TryParse($hostaddress, [ref] $HostIP))) {"Not valid IP address"; return}

# Get Host info
$hostentrydetails = [System.Net.Dns]::GetHostEntry($HostIP)

# Print details:
"Host Name    : {0}" -f $hostentrydetails.HostName
foreach ($alias in $hostentrydetails.alises) {
"Alias        : {0}" -f $alias
}
foreach ($addr in $hostentrydetails.addresslist) {
"Address      : {0}" -f $Addr.ipaddresstostring
}

# End of script