My.Computer.Network.Ping Method

Artykuł
11/16/2012

Pings the specified server.

' Usage
Dim value As Boolean = My.Computer.Network.Ping(hostNameOrAddress)
Dim value As Boolean = My.Computer.Network.Ping(address)
Dim value As Boolean = My.Computer.Network.Ping(hostNameOrAddress ,timeout)
Dim value As Boolean = My.Computer.Network.Ping(address ,timeout)
' Declaration
Public Function Ping( _
   ByVal hostNameOrAddress As String _
) As Boolean
' -or-
Public Function Ping( _
   ByVal address As System.Uri _
) As Boolean
' -or-
Public Function Ping( _
   ByVal hostNameOrAddress As String, _
   ByVal timeout As Integer _
) As Boolean
' -or-
Public Function Ping( _
   ByVal address As System.Uri, _
   ByVal timeout As Integer _
) As Boolean

Parameters

hostNameOrAddress
String. The URL, computer name, or IP number of the server to ping. Required.
address
Uri. The URI of the server to ping. Required.
timeout
Int32. Time threshold in milliseconds for contacting the destination. Default is 500. Required.

Return Value

Boolean indicating whether or not the operation was successful.

Exceptions

The following conditions may cause an exception to be thrown:

No network connection is available (InvalidOperationException).
URL was not valid (PingException).

Remarks

The Ping method is not a fail-safe method for determining the availability of a remote computer: the ping port on the target computer may be turned off or the ping request may be blocked by a firewall or router.

The address passed to the Ping method must be DNS resolvable and cannot be preceded by "http://".

Tasks

The following table lists examples of tasks involving the My.Computer.Network.Ping method.

To	See
Determine whether a remote computer or host is available	How to: Determine if a Remote Computer is Available in Visual Basic

Example

This example reports whether or not the server can be pinged by determining whether the Ping method returns True.

If My.Computer.Network.Ping("198.01.01.01") Then
   MsgBox("Server pinged successfully.")
Else
   MsgBox("Ping request timed out.")
End If

Replace "198.01.01.01" with the IP address, URL, or computer name of the server to ping.

This example reports whether or not the server can be pinged by determining whether the Ping method returned True and specifies a timeout interval of 1000 milliseconds.

If My.Computer.Network.Ping("www.cohowinery.com",1000) Then
   MsgBox("Server pinged successfully.")
Else
   MsgBox("Ping request timed out.")
End If

Replace "www.cohowinery.com" with the IP address, URL, or computer name of the server to ping.

Requirements

Namespace:Microsoft.VisualBasic.Devices

Class:Network

Assembly: Visual Basic Runtime Library (in Microsoft.VisualBasic.dll)

Availability by Project Type

Project type	Available
Windows Application	Yes
Class Library	Yes
Console Application	Yes
Windows Control Library	Yes
Web Control Library	Yes
Windows Service	Yes
Web Site	Yes

Permissions

The following permissions may be necessary:

Permission	Description
FileIOPermission	Controls the ability to access files and folders. Associated enumeration: Unrestricted.
SecurityPermission	Describes a set of security permissions applied to code. Associated enumeration: ControlPrincipal.
WebPermission	Controls rights to access HTTP Internet resources. Associated enumeration: Unrestricted.
SocketPermission	Controls rights to make or accept connections on a transport address. Associated enumeration: Unrestricted.
PerformanceCounterPermission	Controls access to a Windows NT performance counter component. Associated enumeration: Unrestricted.
NetworkInformationPermission	Controls access to network information and traffic statistics for the local computer. Associated enumeration: Ping.

For more information, see Code Access Security and Requesting Permissions.

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