Explanation
The most important factor when planning a network audit is to identify the existing nodes on the network.
Nodes are devices or systems that are connected to the network and can communicate with each other. Nodes can include servers, workstations, routers, switches, firewalls, printers, scanners, cameras, etc. Identifying the existing nodes on the network will help the auditor to determine the scope, objectives, and methodology of the audit. It will also help the auditor to assess the network topology, architecture, performance, security, and compliance. References:
CISA Review Manual (Digital Version)
CISA Questions, Answers & Explanations Database

Section: Protection of Information Assets
Explanation:
VPN is a mature technology; VPN devices are hard to break. However, when remote access is enabled,
malicious code in a remote client could spread to the organization's network. Though choices B, C and D
are security risks, VPN technology largely mitigates these risks.

To trace the topology of the network, a graphical interface would be essential. It is not necessary that each network be on the internet and connected to a help desk, while the ability to export to a spreadsheet is not an essential element.

Distributed denial of service ( DDoS ) attacks are common, where a large number of compromised hosts are used to flood a target system with network requests. One technique to exhaust victim resources is though the use of an attack amplifier - where the attacker takes advantage of poorly designed protocols on 3rd party machines in order to instruct these hosts to launch the flood.