TCP/IP Information
Copyright © 1997 by International Business Machines Corporation

DDNS Server Administrator Help

Roots and Forwarders Tab

Use the Roots and Forwarders tab of the Domain Name Server Notebook to configure roots (root servers) and forwarders and, if you configure forwarders, to designate your name server as a slave server.

The Domain Name System (DNS) provides name-to-address resolution using a hierarchical naming scheme and a distributed database. A root server, which is an authoritative name server for the root domain of its network, can resolve all names in its network, either by doing the resolution itself or by requesting resolution from name servers in subdomains of the root domain (which can, in turn, request name resolution from name servers in the subdomains of those subdomains). A name server contacts root servers when attempting to resolve queries outside its zone of authority (the set of subdomains for which it can resolve names and IP addresses).

An alternative way to resolve names is to use forwarders. When a name server receives a request to resolve a name that is neither in its domain nor stored in its cache, it can forward the request to other name servers designated as forwarders. If the forwarders cannot resolve the name, the request is then routed to the root servers. Over time, the forwarders build up a large cache of information, which reduces the number of requests that have to be routed to the root servers. If you define forwarders for your name server, you can also specify that queries are to be routed only to the forwarders and not to the root servers, thus making your name server a slave server.

The Roots and Forwarders tab has these fields and check boxes:

Root Server
Specifies information about a root server.

Host Name
Specifies the complete name of a name server to add to the root server set, for example:
server1.raleigh.ibm.com
The IP address must accompany the host name; after typing both, click Add.

IP Address
Specifies the IP address (in dotted decimal notation) of a name server to add to the root server set. The host name must accompany the IP address; after typing both, click Add.

List Box
Displays the names and IP addresses of the name servers in the root server set. To remove an entry from the list box, select the entry and click Remove.

Forwarder
Specifies information about a forwarder.

IP Address
Specifies the IP address (in dotted decimal notation) of a name server to add to the forwarder set. to. After typing the IP address, click Add.

List Box
Displays the names and IP addresses of the name servers that are designated as forwarders.To remove an entry from the list box, select the entry and click Remove.

Only query the forwarders and not the root servers
When checked, specifies that the name server is a slave server; that is, only the forwarders are to be queried if the name server cannot resolve a name. This option restricts name resolution to this name server and the forwarders and, therefore, can result in non-resolution of a defined host name. When not checked, host names not resolved by the forwarders are directed to the root server for ultimate name resolution. This check box can be checked only if one or more forwarders are configured.

These push buttons are available on the Roots and Forwarders tab:

Add
Puts the specified item into the corresponding list box.
Remove
Deletes the selected item or items from the list box.
OK
Retains the configuration data in this notebook and closes the notebook.
Cancel
Cancels any actions taken in this notebook and closes the notebook.
Help
Displays information about the current notebook page.


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