Domain Name System (Dns) Resolver; Overview; Dns Resolver Default Configuration; Configuring And Displaying Dns Resolver - Foundry Networks NetIron M2404C User Manual

Foundry NetIron M2404C and M2404F Metro Access Switches

Domain Name System (DNS) Resolver

The Domain Name System (DNS) is the means by which Internet domain names are located and
translated into Internet Protocol addresses. A domain name is a meaningful and easy-to-remember
"handle" for an Internet address.

Overview

You can define up to three DNS servers. If a query to the primary address fails to be resolved after
three attempts, the next gateway address is queried. This process continues for each defined
gateway address until the query is resolved or when all the queries have failed. The order in which
the default gateway addresses are polled is the same as the order in which the user enters them.
DNS is a distributed database with which the user can map host names to IP addresses through the
DNS protocol from a DNS server. When the user configures DNS, the user can substitute the host
name for the IP address with the ping and traceroute commands in Privileged (Enable) mode.
The application software supports a cache mechanism for names that are already resolved. If a
resolve query arrives at the device, the DNS Resolver first searches the requested name in that
cache. If it does not find any match, the DNS Resolver delivers the query to the DNS server. The
TTLs (time to live) of those cache entries are extracted from the Resource Record (RR) of the
server response.
To use DNS, the user must have a DNS name server present on the network.

DNS Resolver Default Configuration

Table 30 shows the DNS Resolver default configuration.
Table 30: DNS Resolver Default Configuration
Parameter
DNS servers

Configuring and Displaying DNS Resolver

Table 31 lists the DNS Resolver commands.
Table 31: DNS Resolver Commands
Command
ip dns server
show ip dns
Setting DNS Server
The ip dns server command, in Global Configuration mode, specifies the IP address of one or
more DNS servers. Up to three DNS servers can be added.
Domain Name System (DNS) Resolver
Description
Specifies the IP address of one or more DNS servers.
Displays the current configuration of the DNS Resolver.
© 2008 Foundry Networks, Inc.
Switch Administration (Rev. 03)
Default Value
None specified
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