174 BigIron RX Series Configuration Guide53-1002253-01Configuring IP parameters7Configuring Domain Name Server (DNS) resolverThe DNS resolver lets you use a host name to perform Telnet, ping, and traceroute commands. Youcan also define a DNS domain on a device and thereby recognize all hosts within that domain. Afteryou define a domain name, the device automatically appends the appropriate domain to the hostand forwards it to the domain name server.For example, if the domain “newyork.com” is defined on a device and you want to initiate a ping tohost “NYC01” on that domain, you need to reference only the host name in the command insteadof the host name and its domain name. For example, you could enter either of the followingcommands to initiate the ping.BigIron RX# ping nyc01BigIron RX# ping nyc01.newyork.comDefining a DNS entryYou can define up to four DNS servers for each DNS entry. The first entry serves as the primarydefault address. If a query to the primary address fails to be resolved after three attempts, the nextgateway address is queried (also up to three times). This process continues for each definedgateway address until the query is resolved. The order in which the default gateway addresses arepolled is the same as the order in which you enter them.Suppose you want to define the domain name of newyork.com on a device and then define fourpossible default DNS gateway addresses. To do so, enter the following commands.BigIron RX(config)# ip dns domain-name newyork.comBigIron RX(config)# ip dns server-address 209.157.22.199 205.96.7.15 208.95.7.25201.98.7.15Syntax: ip dns domain-name Syntax: ip dns server-address [] [] []The first IP address in the ip dns server-address... command becomes the primary gateway addressand all others are secondary addresses. Because IP address 201.98.7.15 is the last addresslisted, it is also the last address consulted to resolve a query.Defining a domain listIf you want to use more than one domain name to resolve host names, you can create a list ofdomain names. For example, enter the commands such as the following.BigIron RX(config)# ip dns domain-list company.comBigIron RX(config)# ip dns domain-list ds.company.comBigIron RX(config)# ip dns domain-list hw_company.comBigIron RX(config)# ip dns domain-list qa_company.comBigIron RX(config)#The domain names are tried in the order you enter them.Syntax: [no] ip dns domain-list sequence-number The parameter specifies the domain name to be added to the list.The parameter specifies a sequence number that is generated internally insteps of 10 starting with sequence number 5. The entries are tried in order of sequence number ofentries.
