.net - Dns.GetHostEntry Error Conditions And Resolution Methods?
Feb 4, 2011
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)?
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Sep 3, 2010
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://", "")
[code]....
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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)
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Jun 8, 2012
Lets say I click a button on a form that calls a function in a data access class. This function inserts a record into a table in a database. The function returns an integer value for the record id of the newly inserted record. Now lets say the insert failed (syntax error, timeout, whatever). I can return a zero to the calling routine to indicate the failure, but not the error message. So in general, what's the most appropriate way to handle getting information back to a calling routine when the return parameter data type doesn't allow it?
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Sep 4, 2011
msgbox(System.Net.Dns.GetHostEntry(System.Net.Dns.GetHostName()).AddressList(0).ToString())
is showing Ip address in Win XP but in Windows 7 it is not showing.
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Dec 5, 2009
How to get list of all resolution of client monitor and check with resolution passed by application
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Jun 1, 2011
I am having some problems in my app for the database timeout. Due to some network glitches the query takes more than 45 sec to return the resultset which has about 10,000 rows. Most of the time its fast upto 11-12 secs. My app is runs as a scheduled job in the background.The problem is I need to try three times if i get the timeout exception before writing the error to the error log or exiting. I know i can set the command timeout property to 60 seconds but still i want to try three times before exiting. I have written a method for that but I think there is some flaw in my method. For now i specifically set the timeout to be 5 seconds as i know well that it takes more than 25 seconds for this stored proc to run. I just want to get that timeout expired exception and write ways to handle it.
My problem is if after 2 times I set the connection timeout to 50 so my method goes and get the correct list but it again goes inside the methodname which i have called inside the catch statement and finally returns nothing. It looks like its getting into recursion or something but i am confused as to where i am wrong.[code]
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Oct 2, 2009
1. Is there anyway to make an application look as though it has been set to a screen resolution of 1024 x 768 when the true resolution different?
2. I am developing my app using a widescreen monitor. What dimensions does the form need to be set to so that it looks exactly the same on a normal & widescreen monitor?
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Oct 22, 2007
I am working on an program and I need it to change the size on the form and the button etc when its ran on a different resolution then it was coded on. Is there anyway to do this easy or do I have to hard code it on two different and change it by like a button etc? I am working with a 1024 X 780 and a 1240 X 1024.
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Jun 12, 2012
Error 4 Overload resolution failed because no accessible 'Where' can be called with these arguments:Extension method 'Public Function Where(predicate As System.Func(Of System.IO.FileInfo, Integer, Boolean)) As System.Collections.Generic.IEnumerable(Of System.IO.FileInfo)' defined in 'System.Linq.Enumerable': Nested function does not have a signature that is compatible with delegate 'System.Func(Of System.IO.FileInfo, Integer, Boolean)'.
Extension method 'Public Function Where(predicate As System.Func(Of System.IO.FileInfo, Boolean)) As System.Collections.Generic.IEnumerable(Of System.IO.FileInfo)' defined in 'System.Linq.Enumerable': 'HasFlag' is not a member of 'System.IO.FileAttributes'.
[code].....
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Jan 10, 2011
I have a very high screen resolution on my laptop: 1400x1050.My colleague tried it out on his laptop (which had lesser resolution), and the application did not fit on his laptop. The buttons were dragging out of the screen space.So, I want my application to automatically resize/adjust based upon the screen resolution.I don't want to use Maximized screen option and don't want to change user's pc settings.Unfortunatly I am not using Table Layout panel.
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Dec 29, 2010
In my application,I placed the user control on a panel,I want to resize that control on a panel automatically according to different screen resolution.
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Jun 18, 2012
Can we set the windows form resolution according to pc screen resolution and even the control should be adjusted...
eg.
My screen resolution is 1366 X 768
and my form size is 1254, 709....but I want it so set according to the screen and it will be dynamic...
if I transfer my project to some other pc with lower or higher resolution it should be adjusted....
and suppose I have few controls on the form...will that also be adjusted??
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Dec 20, 2010
I had designed all forms on 1280/800 screen resolution.
i want set all forms resolution like the current screen resolution of the user,or make the form resolution is dynamic with each resolution of screen for
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Feb 5, 2009
I got data transfer project via tcp/ip. but its give some error..anybody help me to clear that errors. client.Send(buffer, wd, Sockets.SocketFlags.None)Error:Overload resolution failed because no accessible 'Send' can be called without a narrowing conversion: 'Public Function Send(buffers As System.Collections.Generic.IList(Of System.ArraySegment(Of Byte)), socketFlags AsSystem.Net.Sockets.SocketFlags, ByRef errorCode As System.Net.Sockets.SocketError) As Integer': Argument matching parameter 'buffers' narrows from '1-dimensional array of Byte' to System.Collections.Generic.IList(Of System.ArraySegment(Of Byte))'.
[Code]...
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Jun 16, 2010
I've been working on my own version of Notepad/Wordpad and I just tried adding the Find feature for the Rich Text box and I got an error. Here's the code I had:[code]
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Mar 7, 2011
CODE:
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Feb 23, 2009
I am trying to create a program that has a button and a text box. Everytime the button is pushed I want it to add one to the text box. I keep getting this error: Overload resolution failed because no accessible 'Int' accepts this number of arguments?
Option Strict On
Public Class Form1
Private Sub btnPlus_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnPlus.Click
Dim i As Integer = Int.Parse(txtAdd.Text)
i += 1
[code]....
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Sep 11, 2010
I have a little problem here. I am getting an error which they are jumping on this statement: a.Proxy = New WebProxy(Address.Text, Ports.Text). I have removed the equal to replace with the Address.Text and Ports.Text, I have tried to included And statement and the '&' in that statement, but I keep get the messagebox. The ip I am connecting are working well.
Here it is the
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Try
Dim a As HttpWebRequest = DirectCast(HttpWebRequest.Create("http://whatismyip.com/automation/n09230945.asp"), HttpWebRequest)
[code]....
Error: Overload resolution failed because no accessible 'New' can be called without a narrowing conversion: 'Public Sub New(Address As String, BypassOnLocal As Boolean)': Argument matching parameter 'BypassOnLocal' narrows from 'String' to 'Boolean'. 'Public Sub New(Host As String, Port As Integer)': Argument matching parameter 'Port' narrows from 'String' to 'Integer'.
I shouldn't have the messagebox displaying on my screen while I am connect to the ip. I have tried with the dim statement to included the textbox strings, but it doesn't help. how I could included the strings of the textbox in the a.Proxy = New WebProxy statement?
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Apr 25, 2011
This overload resolution failed error that occurs when I try to add the newly created integer array as an item in a generic linked list as per the following?
Imports System.Collections.Generic
Public Class GraphData
Dim mInput As Byte()
Public Data() As Integer
Dim SignalData As New LinkedList(Of Integer)(Data)
Private Sub Paint(ByVal sender As Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles Me.Paint
[Code] .....
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Nov 2, 2010
I'm implementing following code in VS2010:
If xl.cells(1, contacolonna).Borders(Excel.XlBordersIndex.xlEdgeRight).LineStyle <> Excel.XlLineStyle.xlContinuous Then
MsgBox("hello")
End If
or following
[code]....
but in both cases VS returns following error:"InvalidCastException was unhandled Overload resolution failed because no Public '=' can be called with these arguments:'Public Shared Operator =(a As String, b As String) As Boolean':Argument matching parameter 'a' cannot convert from '__ComObject' to 'String'. "
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Aug 29, 2011
This is the original code in c#
public class CategoryRepository: RepositoryBase<Category>, ICategoryRepository
{
public CategoryRepository(IDatabaseFactory databaseFactory)
: base(databaseFactory)
[Code]...
Does anyone has an idea what i should change to let it work and let my UserRepository use the methods in RepositoryBase while implementing the IUserRepository?
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Jun 24, 2011
I am working with a vb program, but there is something strange on one of my .vb code pagewhen i put the "dot" afther the object name its dont show the methods availables for this objectbut on other vb code pages i can see it. but in this one no.for exmaplethis is a piece of code: Dim sb As New StringBuilder()
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Mar 29, 2010
I am not sure how clear my question is by the title, but I am trying to make Class methods instead of Instance methods in Visual Basic that way I don't have to waste memory and code creating temporary objects to execute methods that don't need instance variables.
I am not sure if you can do that in VB but I know you can in Objective-C by using either a "+" or "-" sign in front of the method declaration. And in C++ (at least I think, I can't remember) you put the static keyword or const keyword in front of the function.How would I do this in VB if it is possible? Or should I just make a separate set of functions that are not members of a class?
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Apr 12, 2010
I am getting Error at this line m_frmPrintPreview.vspPrint.Font = New Font(Me.m_frmPrintPreview.vspPrint.Font,FontStyle.Underline) Error is Overload resolution failed because no accessible 'New' can be called without a narrowing conversion: 'Public Sub New(familyName As String, emSize As Single)': Argument matching parameter 'familyName' narrows from 'stdole.IFontDisp' to 'String'.
[Code]...
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Aug 26, 2010
Public Class Form1 Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load Dim someproc As Process
[Code]...
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May 10, 2009
Public Class Inventory_Edit
Private Sub Inventory_Edit_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
'TODO: This line of code loads data into the 'CategoryDataSet.Category' table. You can move, or remove it, as needed.
Me.CategoryTableAdapter.Fill(Me.CategoryDataSet.Category)
[URL]
I added an "edit" icon on my bindingNavigator. When users click on it, a new form will come out and pull out all the data records from the datagridview. Now the strange thing is that when I wanted to edit the data records, when I left the product name blank, I would get an error message saying "Product cannot be blank" - please see above code. But when I left the "Cost Price" blank(same applies to "Sell Price" and "Quantity"), the error message box wouldn't come out, instead, it did not allow me to move on to another textbox, close the form etc until I filled out that textbox with INTEGER. May I know why the error mesagebox would not come out when I entered the wrong datatype?
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Oct 11, 2011
the testBoolean is set to the value True, but for some reason when debugging, it step through both conditions, so in the end the button1.visble becomes False, but I want it to be set to True.[code]....
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Feb 1, 2011
I am very new to vb, I know there is an error somewhere, I had an assignment which stated that if a number was < 101 or > 500 and the answer is correct the output should be, for example-123, if the answer was wrong then the message output should be wrong number <101>500. Everytime I type in a number(no matter what the number) and click on my check button I get the output message. If at all possible, can you please assist. My professor gave the following example, but I am still not getting it:
Dim strInteger As String = "52.801"
Dim dblNumber As Double
dblNumber = CDbl(strInteger)
[code].....
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Jun 20, 2012
I want to use a value that is pulled from the SQL within the if statement. Ideally i want to do the equivalent of <% If DataBinder.Eval(Container, "DataItem.BookID") == 1 Then%> Is there a way to do this with the correct syntax?
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