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Dns.GetHostEntry Method (IPAddress)

.NET Framework 4

Other Versions

Resolves an IP address to an IPHostEntry instance.

Namespace: System.Net
Assembly: System (in System.dll)

Syntax

C++

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public static IPHostEntry GetHostEntry(
	IPAddress address
)

Parameters

address: Type: System.Net.IPAddress
An IP address.

Return Value

Type: System.Net.IPHostEntry
An IPHostEntry instance that contains address information about the host specified in address.

Exceptions

Exception	Condition
ArgumentNullException	address is null.
SocketException	An error is encountered when resolving address.
ArgumentException	address is an invalid IP address.

Remarks

The GetHostEntry method queries a DNS server for the IP addresses and aliases associated with an IP address.

IPv6 addresses are filtered from the results of the GetHostEntry method if the local computer does not have IPv6 installed. As a result, it is possible to get back an empty IPHostEntry instance if only IPv6 results where available for the address parameter.

The Aliases property of the IPHostEntry instance returned is not populated by this method and will always be empty.

Note
This member emits trace information when you enable network tracing in your application. For more information, see Network Tracing.

Examples

The following code example uses the GetHostEntry method to resolve an IP address to an IPHostEntry instance.

C++

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public static void DoGetHostEntry(string hostname)
{
    IPHostEntry host;

    host = Dns.GetHostEntry(hostname);

    Console.WriteLine("GetHostEntry({0}) returns:", hostname);

    foreach (IPAddress ip in host.AddressList)
    {
        Console.WriteLine("    {0}", ip);
    }
}

Version Information

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

.NET Framework Security

DnsPermission
for accessing DNS information. Associated enumeration: PermissionState.Unrestricted

Platforms

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Reference

Dns Class

GetHostEntry Overload

System.Net Namespace

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FAQ

GetHostEntry using IP Address - Sample using PowerShell

<#
.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

History

10/5/2010
Thomas Lee