DNSServer Object (Dundas Mailer Control 1.0)
This object is used with the DNSServers collection.
Remarks
To add DNSServer objects to the DNSServers collection use the collection's Add method. To remove one item call the Remove method of the collection. To clear all objects from the collection use the Clear method.
The DNSServer object consists of the following property:
Name as string. The name of the DNS server to be used, or its corresponding IP address.
TCPIPRetryCount as long. The maximum number of times to attempt to connect to the server using the TCP/IP protocol. Defaults to 1.
- UDPRetryCount as long. The maximum number of times to attempt to connect to the server using the UDP protocol. Defaults to 3.
If the SMTPRelayServers collection is empty then the email message is sent directly to the destination server, so a DNS server is required to determine where the message is to be sent. However, if the SMTPRelayServers collection is not empty then the message is sent using the specified relay server, and the DNSServers collection is ignored since the relay server is responsible for determining where the message is being sent to. If both the SMTPRelayServers and DNSServers collections are empty the DNS server to be used defaults to "A.ROOT-SERVERS.NET". If this fails "B.ROOT-SERVERS.NET" will be tried. If this too fails then "C.ROOT-SERVERS.NET" will be tried. If all of these fail then the mail operation will fail as well.
There are two (2) methods of connecting to a DNS server: using the TCP/IP protocol and using the UDP protocol. Different DNS servers may support either protocol or both protocols. By default the TCP/IP method is tried first. If this fails we then attempt to contact the server using UDP. If you know what protocols your specified DNS servers use you can optimize the DNS lookup operations by specifying which protocol to use when working with the DNS server(s).
Specifying multiple DNS servers (when not using SMTP relays) increases the reliability and performance of your mail operation.
This collection can be used by all mail sending functions (as well as PostArticle), depending on whether SMTP relay servers are being used or not.
See Also: CustomHeaders Collection | Add Method | Remove Method | Item Method | Count Property