Using DNS

This document describes Nx Networks Domain Name Services (DNS) client software. It includes the following sections:

DNS Overview

The DNS client software allows users on your network to use a domain name, rather than an IP address, when running Ping, Telnet, or Traceroute.

In the DNS client services configuration, you set the address of the DNS server that you want the router to query for the IP address of a host name. You can also have a hostname-to-IP address mapping table in your IP configuration that you set up using the add hostname command.

When a user runs Ping, Telnet, or Traceroute using a name, the router software checks for the name in your IP host table. If the name is not there, the router sends a query to the DNS server.

Note that if a name is not in the IP hostname table, and you have not specified the DNS domain name using the domain_name option. you must use the fully qualified domain name, and not just the host name, when running Ping, Telnet, or Traceroute. For example, instead of blandings, you would use blandings.nxnetworks.com.

Displaying the DNS Client Prompts

To display the DNS client configuration prompt, do the following:

*config
Config>protocol ip
Internet protocol user configuration
IP config>dns
DNS Client Config>

To display the DNS client monitoring prompt, enter the following command at the IP> prompt:

*monitor
Monitor>protocol ip
IP>dns
DNS Client>

Configuring DNS

This section outlines the steps needed to configure DNS client on your router.

1. Enable DNS client.

DNS Client Config> enable

2. Set the address of at least one DNS server.

DNS Client Config> set server += 128.185.50.1

3. Restart the router for the new configuration to take effect.

DNS Client Config> exit
IP config>exit
Config> <CTRL-P>
*restart
Are you sure you want to restart the gateway?(Yes or [No]):y

DNS Commands

This section describes the DNS commands.

Press Space after you type a command to display the available options for each command. Enter help for information about using the command line interface.

[C] means the command is available at the DNS Client Config> prompt.

[M] means the command is available at the DNS Client> prompt.

Table 15 DNS Client Commands

Command Function

Disable [C] [M] Disables DNS client on the router.

Enable [C] [M] Enables DNS client on the router.

Exit [C] [M] Returns to the previous prompt level.

List [C] [M] Displays your DNS client configuration.

Revert [M] Restores the configuration saved in permanent memory.

Save [M] Saves changes you make at the DNS Client> prompt to permanent memory.

Set [C] [M] Sets the DNS client timeout. Also adds or removes a domain name or the IP address of a DNS server.

Table 15 DNS Client Commands
Command	Function
Disable [C] [M]	Disables DNS client on the router.
Enable [C] [M]	Enables DNS client on the router.
Exit [C] [M]	Returns to the previous prompt level.
List [C] [M]	Displays your DNS client configuration.
Revert [M]	Restores the configuration saved in permanent memory.
Save [M]	Saves changes you make at the `DNS Client>` prompt to permanent memory.
Set [C] [M]	Sets the DNS client timeout. Also adds or removes a domain name or the IP address of a DNS server.

Disable [C] [M]

Disables DNS client on the router.

Syntax: disable

Example: disable

Enable [C] [M]

Enables DNS client on the router. By default, DNS is enabled. You must have at least one DNS server name configured for DNS to run.

Syntax: enable

Example: enable

Exit [C] [M]

Returns to the previous prompt level.

Syntax: exit

Example: exit

List [C] [M]

Displays the DNS client configuration.

Syntax: list

Example: list

DNS Client Status:   Enabled
Timeout, in seconds: 3600
DNS Server location: 162.23.0.242
                     194.165.1.44
Domain name(s):      nxnetworks.com

Revert [M]

If you make configuration changes at the DNS Client> prompt, this command restores the saved configuration.

Syntax: revert

Example: revert

Save [M]

Saves changes you make at the DNS Client> prompt to permanent memory so they are still present after you restart the router.

Syntax: save

Example: save

Set [C] [M]

Sets the DNS client timeout as well as the IP address of the DNS servers and domain names to use during DNS lookup.

Syntax: set

timeout
server
domain_name

timeout

Sets DNS client timeout timer, in seconds. If the DNS server does not respond to DNS client queries within this timeout period, the DNS client stops sending requests to the server.

The default setting is 15 seconds. The range is 1 to 3600 seconds.

Syntax: timeout = #-of-seconds

Example: set timeout = 600

server

Adds or removes a DNS server to use for DNS lookups. You can specify the IP address of one or more DNS servers to which DNS will direct queries. DNS requires that you specify at least one server.

Syntax: server

+= IP address
-= IP address
Use . . . To . . .

+= IP address Add a DNS server

-= IP address Remove a DNS server

Use . . .	To . . .
+= IP address	Add a DNS server
-= IP address	Remove a DNS server

Example: set server += 192.168.3.3

domain_name

Adds or removes a domain name to use for DNS lookups. You can specify one or more domain names to which DNS will direct queries. DNS does not require that you specify a domain name. However, we recommend that you add the domain name of your local network so that you do not have to specify fully qualified domain names with a ping command. For example, if your local domain name is nxnetworks.com and you add this domain name, you can use the shorter command ping blandings instead of typing ping blandings.nxnetworks.com.

Syntax: domain_name

+= domain
-= domain
Use . . . To . . .

+= IP domain Add a domain name

-= IP domain Remove a domain name

Use . . .	To . . .
+= IP domain	Add a domain name
-= IP domain	Remove a domain name

Example: set domain_name += nxnetworks.com

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