Cisco CCNA Certification Exam Tutorial: The OSI Models Physical Layer
To pass your CCNA exam and earn this coveted certification, you’ve got to master the seven layers of the OSI model and what each layer does. For those of you taking the two-exam path, you can expect quite a few OSI model questions on the Intro exam. In this seven-part series, we’ll spend some time taking a look at each of the OSI model layers, starting with the Physical layer.
Often, CCNA candidates ask if the OSI model has any practical uses for network administrators. I used to wonder the same thing, and I can now tell you that the answer is definitely yes!
The OSI model isn’t something you want to memorize and then forget about, as using the OSI model gives you a structured approach for troubleshooting. Whenever a network device isn’t working properly, I always say to “start at the physical layer”. The Physical layer is Layer One of the OSI model, and this is where troubleshooting should always start. Is the device on? Is it properly connected? If everything is fine at Layer One, you just move up to Layer Two, and continue in this structured...