Patton electronic SmartNode 4110 Series DNS configuration task list, Enabling the DNS resolver

SmartWare Software Configuration Guide 28 • DNS configuration

Introduction

The domain name system (DNS) enables users to contact a remote host by using easily remembered text labels (www.patton.com, for example) instead of having to use the host’s numeric address (209.45.110.15, for exam- ple). When DNS names are entered as part of configuration commands or CLI exec mode commands in appli- cations like Ping, Traceroute, or Tftp, the SmartNode uses a DNS resolver component to convert the DNS names into the numeric address.

The SmartNode can be configured as a caching DNS relay server to speed data transfers, acting as the DNS server for a private network. In this configuration, hosts in the network send their DNS queries to the Smart- Node, which checks to see if the DNS name is in its DNS resolver cache. If it finds the name in cache, the SmartNode uses the cached data to resolve the DNS name into a numeric IP address. If the name is not in cache, the query is forwarded on to a DNS server. When the SmartNode receives the answer from the server, it adds the name to the cache, and forwards it on to the host that originated the query. This process enables the SmartNode to provide answers more quickly to often-queried DNS names, reducing the number of DNS que- ries that must be sent across the access link.

DNS configuration task list

The following sections describe how to configure the DNS component:

•Enabling the DNS resolver

•Enabling the DNS relay

Enabling the DNS resolver

To enable the SmartNode DNS resolver, you must configure it with the address of one or more DNS servers that will be used to resolve DNS name queries. If multiple DNS servers are configured, the SmartNode will query each server in turn until a response is received. DNS servers are configured as follows:

Mode: Configure

Step	Command	Purpose
1	node(cfg)#dns domain-name server	Add an IP address of a DNS server to be used
	server-ip-address	resolving DNS names
2		Repeat step 1 for each additional DNS server
		you want to add
2	node(cfg)#dns-client cache number-of-entries	Optional. Defines the maximum number of DNS
		answers stored within the cache (default is 30)

Example: Configuring DNS servers

The following example shows how to add DNS servers to the SmartNode DNS resolver and increase the size of the DNS cache to 100 entries.

node>enable

node#configure node(cfg)#dns-client server 62.2.32.5 node(cfg)#dns-client server 62.2.100.45 node(cfg)#dns-client cache 100

Introduction 305