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  • Your email address will not be published.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

  • Live Event Date: March 19, 2015 @ 1:00 p.m. ET / 10:00 a.m. PT The 2015 Enterprise Mobile Application Survey asked 250 mobility professionals what their biggest mobile challenges are, how many employees they are equipping with mobile apps, and their methods for driving value with mobility. Join Dan Woods, Editor and CTO of CITO Research, and Alan Murray, SVP of Products at Apperian, as they break down the results of this survey and discuss how enterprises are using mobile application management and private …

  • Live Event Date: March 18, 2015 @ 2:00 p.m. ET / 11:00 a.m. PT Content is king, and businesses of all kinds want to leverage content to demonstrate their business benefits to customers, prospects, and partners alike. With new media options – 4K, 3D, HTML, and new devices – all becoming a part of your communications strategy, what tools are there that can speed time to value while reducing learning curve and duplication of efforts? Check out this upcoming eSeminar to learn how working with Adobe …

Most Popular Programming Stories

More for Developers

RSS Feeds

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