System.Net.Dns.GetHostEntry Doesn't Throw Error If Unable To Resolve?
Nov 13, 2009
I want to check if an IP address can be resolved to a hostname.I figured I would use System.Net.Dns.GetHostEntry as System.Net.Dns. GetHostByAddress is shown as obsolete in VS2008.
However,if I specify an invalid IP address to System.Net.Dns.GetHostEntry the HostName property equals the IP address I gave. If I use System.Net.Dns.GetHostByAddress it, rightly, gives a resolution error.I don't mind continuing to use System.Net.Dns. GetHostByAddress but is there any way to have System.Net.Dns.GetHostEntry throw an error if the IP address cannot be resolved to a hostname (other than by checking if the IP address given equals the hostname returned, I mean)
So i've been working on a page for a project where the person logs into a login page and then can see a list from the database of employees. everything is working except for one problem. If someone puts in a username and password, username= a and password=b, for example it still allows that individual to view the next page and doesn't throw the error that i have enbedded on the login page to say sorry you have the incorrect password/username. The working code that i have so far is below:
I am creating a TCP socket on port 21 using server hostname.The code work fine in my laptop but when i test in a device with WindowsXPe , i am getting a Dns.Resolve error as "The type initilizer for system.Net.Dns threm exception"
Basically Im a vba programmer and Iam facing a serious problem with the checkbox controls of the VBA.I have to select and deselect the checboxes as per user selection. I believe this is a general question for vb.net also.some sample code
sub chk3_Click() if userform.chk3.value = true then userform.chk4.value = true userform.chk2.value = true end if
I have been trying to trace a list of urls by using the url to get the ip and then use that to assign it a country. When using DNS.gethostentry or even DNS.gethostbyname I get the following error:
SocketExceptionwascaught: No such host is known
Now I even tried fetching the url first using httpwebrequest to ensure the url is valid but the error keeps showing up regardless. I know there are a few urls that don't work but I thought my code would catch and continue.
Try For Each prod In querylist If myfetcher.getHtml(prod, userAgent, page) Then prod = Regex.Replace(prod, "http://", "")
I have a very specific problem concerning Dns.GetHostEntry.A service uses Dns.GetHostEntry to retrieve all IP Adresses of a host, using the name of of the host. This has always worked fine. At a specific customer, Dns.GetHostEntry throws the "no such host is known" error when querying specific hosts. The problem only occurs when trying to resolve hosts that are on a different domain than the machine the service is installed on. The service has worked for quite some time, but recently is stopped working, throwing the "no such host is known" error (sadly, no stack trace is available). Nslookup works though, no problems there.The service in question is written in VB.NET, targetting the .NET Framwork 2.0.The comments in the MSDN entry for .NET 3.0 (http:[url]....aspx indictate that there may be a problem with the reverse DNS entries for the hosts, but I was not able to reproduce the problem on a test network, even with all reverse lookup zones deleted (there are more comments for other .NET Versions, all having similiar problems). [EDIT:] Even deliberatly addind a wrong PTR record does not make the problem occur on my test machine.[EDIT2:] The only thing that made the error come up was disconnecting the network adapter, and thereby making the DNS Server unavailable, even though the forward resolving still worked due to caching.So, my questions are: Under which conditions does GetHostEntry throw this specific error? Which resolution methods does it use? If I'm not mistaken it uses the unmanaged WinSock function getnameinfo (http:[url]....: "Name resolution can be by the Domain Name System (DNS), a local hosts file, or by other naming mechanisms".Any ideas why this suddenly fails for machines on the other domain (but not for machines on the same domain)?
2012-03-16 19:15:09Z E System.NullReferenceException: Object reference not set to an instance of an object. at System.Timers.Timer.set_Enabled(Boolean value) at System.Timers.Timer.Stop()
Here's the code:
Timer declared as private member variable. Private _myTimer As System.Timers.Timer Initialize timer method.
[code]....
The timer has to have a value or else the Timer.Stop() call would be throwing the exception. This is a sporadic error and I'm just trying to see if anyone has experienced this before or if anyone has any ideas of what could be causing it. It is occuring in a WinForms application in the event handler for the Elapsed event of the Timer, but it is only occuring sporadically on the users computer. I haven't been able to reproduce the error myself.
I imported a website made in visual studio express 2008 to visual studio express 2010. When I run the home page I get the following error:"It is an error to use a section registered asallowDefinition='MachineToApplication' beyond application level. This error can be caused by a virtual directory not being configured as an application in IIS."
I have an InvalidCastException Error in my program. The program is that i try to insert an employee record into a database table after getting the details from a form. I've used Money data type is SQL Server for salary and SqlTypes.SqlDecimal data type in employee template class. i've used a stored procedure to pass the values and i add the basic value by passing a parameter by the method
Dim prm8 As SqlParameter = com.Parameters.Add("@basic", SqlDbType.Money) prm8.Direction = ParameterDirection.Input prm8.Value = emp.Bsc
I've used the money datatype itself even in the stored procedure variable.I get the following error.
failed to convert parameter value from sql decimal to decimal Even if i use prm8.Value = Convert.ToDecimal(emp.Bsc)
I get an error Unable to cast object of type 'System.Data.SqlTypes.SqlDecimal' to type 'System.IConvertible'.
I am getting this error when I am tring to load string type to data table)
Using connection As New SqlConnection("connectionstring;") connection.Open() Using Command As New SqlCommand("SELECT ClientId,forename,surname from t_clientdetails
This error first appear to occur randomly. Steps to recreate:Open Visual Studio and load a solution (some files automatically opened) - this is when the problem occurs Close all open files Restart visual studio and load solution (no issues)Open Exactly the same files again, restart visual studio and load solution so files open automatically (problem occurs!)
However, when trying to narrow it down to a single file (that is automatically opened when the solution is loaded), I couldn't reproduce the problem. Now with all the files open again the problem doesn't occur!!! So it looks like it is fixed - though this happened before and eventually the issue came back.
I think it is to do with one of the user controls with DevExpress controls on it - when the error occurs, the designer displays the error. Though I can't reproduce it at the moment to confirm that.
I have below installer class to ngen app after installation and I'm getting several errors.
Imports System.Collections Imports System.ComponentModel Imports System.Configuration.Install 'This line gives warning: Namespace or type specified in the Imports
I try to install Visual Basic 4-32bit on Vista Business but I get an error message 'VBCustom_Controls_Actions_Reg_Graph was unable to register itself in the system registry' ; is there a way to get around it ?
Why does System.Xml.XmlDocument.LoadXml method throw System.Net.WebException ?if MSDN was right, LoadXml should at most give me a System.Xml.XmlException.Yet I have weird exceptions like:The underlying connection was closed: The connection was closed unexpectedly.
Dim document As New XmlDocument document.LoadXml("<!DOCTYPE html PUBLIC ""-//W3C//DTD XHTML 1.0 Transitional//EN"" ""http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd""><x></x>") MsgBox(document.LastChild.Name)
I made an aplication on windows XP and VB.Net 2008 and works fine, but I moved to Windows 7 and Visual Studio 11 Beta and it wont let me build my aplication and displays this error When I double click on the error msg a window pops up a says "There is no editor available for C:(file path)AssemblyInfo.vb
I'm writing it again, i'm developing an app in which user click a picture through image and image will be stored in sdcard then I have choose the picture from image view and send that picture to the server. I have convert my image into the byte array and then encoded it in Base64 string format but when i try to send that image to the server it give me an error of soap fault. Here's the my code of android device:
public void doneImage(){ ByteArrayOutputStream out = new ByteArrayOutputStream(); bitmap.compress(CompressFormat.JPEG, 100, out);
I Have just been watching a video on throwing Exceptions. Are you supposed to throw System.Exceptions from within your custom classes. to the calling code, Which other way can they communicate. I have read in several places it is bad practice to throw SystemExeptions.
Unable to cast object of type 'System.Windows.Forms.MouseEventArgs' to type 'System.Windows.Forms.DataGridViewCellMouseEventArgs'.
Private Sub NoteGrid_CellContentClick(ByVal sender As System.Object, ByVal e As System.Windows.Forms.DataGridViewCellEventArgs) Handles NoteGrid.CellContentClick Try
I wanted a Message Box to appear when a file can't be found, for example. I made a Combo Box (ComboBox1) and a button, this is what the code was:[code]If a file can't be found, I want a message box to appear, not an Error Provider, I tried this code, but it did not work:[code]
I'm trying to convert a batch of .pngs to .jpgs, as in this question:
[Code]....
The call to jpg.Save, however, with a "generic error" in GDI+. Originally outside of the innermost Using statement, I moved the call inwards as per this answer, but it didn't change anything. I have verified that newfile contains a valid path, and that the program has write access to the directory. What am I missing?
I am updating a legacy application, and it was reading a dll from another project for a Dictionary(of Guid, String) of items and using them.
The requirements have changed, and the method that was returning the Dictionary is now returning an IList.
This is the odd behavior of this; the intellisense is not throwing a cast error, nor is the compiler. It does not throw an error until runtime when it tries to set the Dictionary to the IList.
Example:
Dim someDictionary As Dictionary(Of Integer, String) = New Dictionary(Of Integer, String) Dim someList As IList(Of Integer) someDictionary = someList
Below, why doesn't Throw maintain my originating line number? If I run the DerivedPage, my log file lists the error as line 7. Shouldn't it say line 4? It would make sense if I had Throw ex, but I don't. Isn't Throw by itself just supposed to rethrow and bubble up the error? If I remove the Try...Catch block entirely in DerivedPage, then my log file correctly lists 3 as the error line, but I am not able to log any info in case of an error. What can I do to maintain my DerivedPage, and still have my log keep the correct line number?
Public Class DerivedPage Inherits BasePage Page_Load(o,e) Try
[CODE]...
Base page:
Public Class BasePage Protected Overrides Sub OnError(e) MyBase.OnError(e)
[CODE]...
Log.Error does output the InnerException if it exists. It does in this case. However, the stack trace for the InnerException doesn't contain a line number, just the Exception details.
I have a series of API calls that are returning J# data types. I have been able to convert most of the data types (Integer, Boolean, Double, Float, etc) just fine.What I need to do now is convert a java.Util.Collection to a VB .NET collection (ArrayList)
Here is my attempt:
Public Function MakeDotNETCollection(ByVal javaCol As java.util.Collection) As Collection Dim dotNetCol As Collection
[code]....
I keep getting a runtime error "Unable to cast object of type 'AbstractListlistIterator' to type 'System.Collections.IEnumerator.
I am using a background worker and am attempting to use the following code. However I keep getting this error on i "Unable to cast object of type 'ObjectCollection' to type 'System.Array'."
Private Sub btnVerify_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnVerify.Click myArray = listProxies.Items() BackgroundWorker1.RunWorkerAsync() End Sub
I have been trying to use vb2008 to automatically update CustomDocumentProperties fields that I have set up within a pro-forma document. I can load the Word application and word document without problems.I want to update the CustomDocumentProperties fields with data read from a dB. To do this I am assuming that I need to iterate through the CustomDocumentProperties fields within the word document and when one is "found" that matches the data I wish to merge then assign the dB value to the field.The problem is that I am getting an exception error when I try to reference the document customdocumentproperties
"Error : Unable to cast the COM object of type 'System._ComObject' to interface type 'Microsoft.Office.Interop.Word.CustomProperties'. ...... "
my code looks like;
Dim WordApp As Word._Application Dim odoc As Word._Document Dim BContinue As Boolean = True
