202 PART 2 | Technical Overview of Network Security, Firewalls, and VPNs · Assume you may become a victim of a denial of service (DoS) attack. Every communications system is vulnerable to DoS. Do not forget that physical damage can be an effective DoS. · Learn from your mistakes. When a problem is uncovered, when a design flaw is revealed, when a process is shown to be ineffective, lean in, take the hit, own up to the responsibility, and then deal with it. Improve the environment to resolve the issue. Review the process and learn from it. A security checklist can be an effective tool in managing and maintaining network security. Make it a point to start your list now and use it in real-world review immediately. Network Security Troubleshooting Security troubleshooting aims at recovering from problems related to the counter- measures themselves. Problems will occur with the defense mechanisms themselves. Downtime of a security control is as critical as downtime of a core business process or asset. Troubleshooting failures of security controls is an important part of network security management. As with most concerns, prevention is always preferable to repair or response. By