David L. Prowse(A+, Security+, Network+), currently a network security engineer, is creator of Guru Computer Traning Inc., a web-based training company. He has personally trained more than 2,000 Security+ candidates, and is author or co-author of several certification guides, includingExam Cram: A+,A+ Exam Certification Guide, andCompTIA Network+ Video Mentor. He has consulted for several Fortune 1000 companies, and teaches A+, Network+ and Security+ certifications both in the classroom and via the Internet.