DNS Server

(required) The TCP/IP address of your domain name server.

ListManager will have to be shutdown and restarted in order for a change to this setting to take effect.

Note: If your DNS server is not working, or you give an invalid DNS TCP/IP address in this setting, that ListManager will no longer be able to send email out. In most cases, the installer will have placed an appropriate value here.

ListManager will verify any setting you enter by connecting to the IP address you specify, on port 53. If it cannot verify that the DNS server setting is valid, it will not save the setting you specify, and you will receive a warning message to this effect.

You can specify as many DNS servers as you like. Each TCP/IP address must be on a separate line. If you specify more than one DNS server, ListManager will automatically balance the DNS query load between them. Also, if one of your servers goes down, it will still be able to send mail if you have multiple DNS servers defined. Note: Because ListManager uses an internal DNS caching scheme, the DNS cache is equally as effective with one or many servers -- thus, the usual reason for using just one DNS server (to help that server cache entries) does not apply with ListManager.

We recommend that busy sites define as many DNS servers as possible. DNS operations typically are typically a large part of the work in delivering mail, and when there is a great deal of mail to deliver, DNS server efficiency tends to suffer. Thus, listing many DNS servers will increase your mail sending capacity.