CSDNS



Click here for a larger image.

Environment: VS7, C#, .NET

This program is an example of using the DNS class to resolve host names to IP addresses and, where available, resolves host names from IP addresses. The methods for doing this are similar to the sockets functions gethostbyname and gethostbyaddr. Not all IP addresses resolve into host names; it depends on the DNS server, which may or may not have a reverse mapping defined. There also are asynchronous methods for doing the same functions. There even is a method, Dns.Resolve, that determines whether an IP address or host name is used and calls the appropriate method.

//-------------------------------------------------------
private void HostNameButtonClick(object sender,
                                 System.EventArgs e)
{
  m_status.Text = "Trying....";
  m_status.Update();
try
{
  IPHostEntry hostInfo = Dns.GetHostByName(m_host_name.Text);
  m_ip_address.Text    = hostInfo.AddressList[0].ToString();
  m_status.Text        = "ok";
}
catch (Exception excpt)
{
  m_status.Text = excpt.Message;
  m_ip_address.Text = "";
}
MessageBeep(1000);
}
//-------------------------------------------------------
private void IPAddressButtonClick(object sender,
                                  System.EventArgs e)
{
  IPAddress ipaddr = IPAddress.Parse(m_ip_address.Text);
  m_status.Text    = "Trying....";
  m_status.Update();
try
{
  IPHostEntry hostInfo = Dns.GetHostByAddress (ipaddr);
  m_host_name.Text     = hostInfo.HostName;
  m_status.Text        = "ok";
}
catch (Exception excpt)
{
  m_status.Text    = excpt.Message;
  m_host_name.Text = "";
}
  MessageBeep(1000);
}
//------------------------------------------------------
private void ResolveButtonClick(object sender,
                                System.EventArgs e)
{
  m_status.Text = "Trying....";
  m_status.Update();
try
{
  IPHostEntry hostInfo = Dns.Resolve(m_resolve_text.Text);
  m_ip_address.Text    = hostInfo.AddressList[0].ToString();
  m_host_name.Text     = hostInfo.HostName;
  m_status.Text        = "ok";
}
catch (Exception excpt)
{
  m_status.Text = excpt.Message;
  m_ip_address.Text = "";
}
  MessageBeep(1000);
}
//------------------------------------------------------

Downloads

Download demo project - 20 Kb


Comments

  • There are no comments yet. Be the first to comment!

Leave a Comment
  • Your email address will not be published. All fields are required.

Top White Papers and Webcasts

  • On-Demand eSeminar DevOps and Cloud are all the rage in IT, but the two terms relating process and computing aren't mutually exclusive. Join us to see how your movement into cloud changes the way you develop, deploy, test and manage, and how DevOps can actually be a good thing when coupled with cloud.

  • On-demand Event Event Date: May 18, 2015 While the idea of using facial and/or gesture recognition to create a modern, intuitive game seems attractive, some developers may want to leverage Unity 3D as a way to accelerate their development efforts. There are many different ways in which Intel and Unity Technologies have been working together to help speed the development of games with the Intel&reag; RealSense™ SDK (software developer kit). Check out this webcast to join a panel of experts as they …

Most Popular Programming Stories

More for Developers

RSS Feeds

Thanks for your registration, follow us on our social networks to keep up-to-date