Specifying DNS Parameters

You can fine-tune some of the parameters used by the Domain Name System (DNS) Resolver of the Novell BorderManager 3.8 proxy server.

To change DNS parameters:

1. In NetWare Administrator, select the Novell BorderManager 3.8 Setup page for the server.

2. Click DNS then specify TCP or UDP (the default) as the transport protocol used by the DNS Resolver to query the DNS name server.

   If you select UDP and notice an increase in Bad Gateway error messages while the origin Web server is running, you might want to increase the DNS Resolver Timeout value.

3. For UDP, specify the DNS Resolver Timeout value.

   This value indicates how long the proxy server waits before timing out after it sends a request to a DNS name server to resolve a domain name.

4. Specify values for the following parameters:

   • Negative DNS Lookup: How long a failed DNS lookup domain name remains in the proxy server cache. If the proxy server cannot resolve a domain name, it stores that information in its cache for the specified amount of time.

     If the proxy server receives requests for that domain name within this period, it will send a Bad Gateway error message to the browser and will not resolve the domain name again.

   • Maximum DNS Entry TTL: The maximum amount of time that DNS entries are cached before they expire. This is the maximum value, regardless of the value returned by the DNS name server.
   • Minimum DNS Entry TTL: The minimum amount of time that DNS entries are cached before they expire. This is the minimum value, regardless of the value returned by the DNS name server.
   • Maximum DNS Entry Threshold: The maximum number of DNS cache entries. When this number is reached, the proxy server deletes old entries to make room for newer ones. The default is 2,500.

5. Click OK, then click OK again from the Novell BorderManager 3.8 Setup page.