By default, any single word entered on an IOS device that is not recognized as a valid command is treated as a hostname to which you want to telnet. The device will try to translate that word to an IP address in a process that can last about a minute.
Consider the following example:
R1#writte Translating \"writte\"...domain server (255.255.255.255) % Unknown command or computer name, or unable to find computer address
In the output above you can see that I’ve mistyped the command write. The router entered the DNS resolution process which lasted about a minute. This can be annoying and this is why this feature is often turned off, especially in the lab environments.
If you don’t need to have a DNS server configured for your router, you can use the no ip domain-lookup command to disable the DNS translation process:
R1(config)#no ip domain-lookup
Now, if I mistype a command, the router will not perform a DNS resolution process:
R1#writte Translating \"writte\" % Unknown command or computer name, or unable to find computer address R1#
Prerequisites for 200-301
200-301 is a single exam, consisting of about 120 questions. It covers a wide range of topics, such as routing and switching, security, wireless networking, and even some programming concepts. As with other Cisco certifications, you can take it at any of the Pearson VUE certification centers.
The recommended training program that can be taken at a Cisco academy is called Implementing and Administering Cisco Solutions (CCNA). The successful completion of a training course will get you a training badge.
Full Version 200-301 Dumps