DNS .NET (C#, VB.NET, ASP.NET)

The product includes numerous VB.NET, C# and ASP.NET sample applications. All samples include complete source code. For more detailed sample code please refer to the sample applications.

DNS Forward Lookup

Listing 1 demonstrates using the synchronous Lookup method to perform a DNS forward lookup (resolving a host name to an IP address).

`Dim dnsClient as New DnsClient() Dim ipAddresses As IPAddress() ipAddresses = dnsClient.Lookup("www.componentspace.com") For Each ipAddress As IPAddress In ipAddresses ' Process the IP address Next`

Listing 1 DNS forward lookup

DNS Reverse Lookup

Listing 2 demonstrates using the synchronous ReverseLookup method to perform a DNS reverse lookup (resolving an IP address to a host name).

`Dim dnsClient as New DnsClient() Dim hostNames As String() hostNames = dnsClient.ReverseLookup(IPAddress.Parse("64.26.22.64")) For Each hostName As String In hostNames ' Process the host name Next`

Listing 2 DNS reverse lookup

Querying a DNS Server

Listing 3 demonstrates using the synchronous Send and Receive methods to communicate with a DNS server. Request construction and accessing the details in the response message is made easy by using the DnsMessage class.


' Lookup a local DNS server to query
Dim dnsServers As IPAddress()

dnsServers = dnsClient.DnsServerList

Dim dnsClient as New DnsClient(dnsServers(0))

' Construct the DNS request message and send it
Dim request As New DnsMessage()

request.OpCode = CInt(dnsMessage.OpCodes.Query)
request.RecursionDesired = True
request.DnsQuestions.Add(New DnsQuestion(textBoxDomainName.Text, _
    Convert.ToUInt16(queryTypeMap(comboBoxQueryType.Text)), _
    Convert.ToUInt16(DnsQuestion.QClasses.IN)))

dnsClient.Send(request)

' Receive the response
Dim response As DnsMessage

response = dnsClient.Receive()

' Process the response

Listing 3 Querying a DNS server