Disabling DNS Server Lookup

When you type something (at the user or privileged prompt) that the router doesn’t recognize as a command, it assumes that you want to telnet there. So it telnets there if it’s an IP address, or looks in the config for a host table if you typed a word. If the word can’t be resolved to an IP address via a host table, the router broadcasts for a DNS server. This is good if what you typed was an IP address or host name that you want to telnet to—it means you don’t have to type the word “telnet.” This is bad if you just mistyped a command. It ties up the router until the DNS request times out. You can turn off the DNS request with the command no ip domainlookup at the global config mode.

Example:Router#debag

Translating “debag”…domain server (255.255.255.255)

(255.255.255.255)

Translating "debag"...domain server (255.255.255.255)

% Unknown command or computer name, or unable to find computer

address

Router(config)#no ip domain-lookup

Router(config)#^Z

Router#debag

Translating "debag"

Translating "debag"

% Unknown command or computer name, or unable to find computer address

Source: Global Knowledge Training 

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Setting the Console Speed

To connect via the console to a Cisco device, your terminal emulation program needs to be set to the following specifications. (Later in this paper, we’ll tell you how to change the console speed.) Baud rate: 9600 bps, Data bits: 8, Parity: None, Stop bits: 1, Flow control: None. These are the default settings for both the console and the auxiliary ports.

Although the console port defaults to a blazing 9600 bps, some router models will allow you to increase the console speed to as high as 115200. Increasing the console speed has its advantages. At face value, it will enhance the response time when typing at the console and will allow console messages to be sent to the console faster. But more importantly, it is useful for those times when you have to upgrade the IOS through the console port. To change the console speed, you simply use the speed command in line-configuration mode for console 0. The syntax for the speed command is speed . Options may vary on different platforms. Once you change the console speed, you will no longer have console access through your existing terminal setting. You will have to change the console setting on your terminal emulation program to match.

Example:

!

line console 0

speed 115200

READ MORE - Setting the Console Speed

Cisco IOS Deprecated Commands

There are some commands that are officially no longer supported by Cisco, but that still work on most devices. A few of these commands are shorter than their modern-day replacements, so using them can speed up your configuration. Some commonly used ones include:

Old Command

wr (write memory)

wr er (write erase)

who

whe (where)

New Command

copy run start (copy running-config startup-config)

erase start

show users

show sessions

Source: Global Knowledge Training 

READ MORE - Cisco IOS Deprecated Commands