Configuring Domain Name System (DNS) Characteristics

A local name server is any name server that is authoritative for the default domain of the access server. Before adding a local name server, you must first define the access server domain name. The following example shows how to enter a local Internet name server:

Local> CHANGE INTERNET NAMESERV NAMED.ACME.COM ADDRESS 99.99.99.99 LOCAL

You can use a relative domain name if you are defining a local name server for the default domain only.

Configuring a Name Server for a Different Domain

To enter a locally defined name server for a domain other than the access server default domain, follow these steps:

Step Action

1Use the SET INTERNET NAME RESOLUTION DOMAIN command to change the access server default domain name temporarily.

Note:

Temporarily changing the default name affects the ability of other users in resolving relative domain names.

2Use the SET/DEFINE/CHANGE INTERNET NAMESERVER domain-nameADDRESS n.n.n.n LOCAL command to add the name server.

3Change the access server default domain name back to the original domain name.

Name Resolution and Gateways

The access server uses the learned name servers to perform name resolution when using REMOTE or ORDERED name resolution modes. The list of learned name servers for a given domain are, in general, a superset of those explicitly entered with the CHANGE INTERNET NAMESERVER command. The access server primes the cache for the server’s default domain by sending queries to the configured name servers. The queries request the names of all authoritative name servers for the default domain.

The access server may not be able to reach a learned name server because of subnet access restrictions on the access server itself. In this case, the access server flags the unreachable name server and stops using it for name resolution. The access server cannot reach a name server if it is not in the same subnet or there is no gateway to it.

7-14 TCP/IP Network Characteristics