A far more accurate source of information about the existing customer network is obtained through auditing. Generally speaking, auditing involves using various methods, tools, and IOS commands to gather information about the current status of the network.
For example, a company may already have a network management system like HP OpenView deployed that could be used to generate network topology maps, provide performance-related information, and more. Similarly, various IOS commands can also be used to gather information of the status of any existing Cisco equipment. Ultimately, this auditing information will help to paint a more realistic picture of the current network environment.