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DNS actions of a Cisco router are important issues for both the CCNA exam and real-world production networks, and you probably did not know there were therefore many DNS details before you began monitoring for the exam! In this article, we'll look at the ip address name-server command and its proper usage. 

When a command is mistyped on a router, the default behavior of the router is to try and resolve it via DNS. First, the router looks for an IP Host dining table on the neighborhood router to perform this solution thats what the converting word in the result is referring to. A broadcast will be sent by the router within an attempt to resolve this name through a remote DNS server, if theres no IP Host table or the IP Host table doesnt include an entry for that which you typed. To avoid this broadcast, enter the global command no ip domain-lookup. Obviously, to utilize DNS to solve hostnames, internet protocol address domain-lookup would have to be reenabled if its been switched off. 

R2#contin 

Converting "contin."..domain server (255.255.255.255) 

Revisit Unknown command or computer name, or struggling to find computer address 

A demand is mistyped as contin. The Cisco modems default behavior is to resolve this access locally via an INTERNET PROTOCOL ADDRESS Host table, which can be not present on the switch. A broadcast is then delivered to find the name resolution to be performed by a DNS server. The DNS lookup attempt must time out ahead of the setup can carry on. 

R2#conf t 

R2( config )#no internet protocol address domain-lookup 

R2#contin 

Converting "contin" 

Tshirt Not known command or computer name, or not able to find computer address 

Without internet protocol address domain-lookup configured, the router doesnt make an effort to look for a remote DNS server. It sees there is no local resolution designed and almost immediately sends a note to the console that the name cant be resolved. 

R2#conf t 

R2( config )#ip domain-lookup 

R2( config )#ip name-server 10.1.1.1 

R2#contin 

Converting "contin."..domain server (10.1.1.1) 

A DNS server is installed on the community with the INTERNET protocol address 10.1.1.1. DNS lookup is reenabled with the command ip domain-lookup, and the IP address of the DNS server is given with the ip name-server command. 

It's that an easy task to tell a Cisco router exactly where the DNS server is! [http://www.entrust.net/ digital signature]