Answers to the Chapter 3 QA Section

1 Name the seven layers of the OSI model. Application (Layer 7), presentation (Layer 6), session (Layer 5), transport (Layer 4), network (Layer 3), data link (Layer 2), and physical (Layer 1). Some mnemonics to help you recall the names of the layers are All People Seem To Need Data Processing (Layer 7 to 1), Please Do Not Take Sausage Pizzas Away (Layer 1 to 7), and the ever-popular Pew Dead Ninja Turtles Smell Particularly Awful (Layer 1 to 7). 2 What is the main purpose(s) of Layer 7 Layer 7...

Default Routes and the ip classless Command

When a router needs to route a packet and there is no route matching that packet's destination in the routing table, the router discards the packet. Default routing lets the router forward the packet to some default next-hop router. Default routing is that simple However, two configuration options for default routing make it a little tricky. Also one other option changes the algorithm of how the router decides whether there is a routing table match, which affects when the default route is used....

Four Steps to Answering IP Addressing Questions

You must master IP addressing and subnetting to succeed as a network engineer. To pass the CCNA exam, you must at least be able to answer a few questions about subnetting. For most networking jobs, the ability to think about IP addresses and quickly decipher the structure and meaning of the address is a prerequisite for the job. The exam will test your abilities with questions that go something like this Given a network number and a mask, how many subnets are there, and how many hosts are there...

Comparison of LAN Segmentation Using Bridges Switches and Routers

The CCNA exam tests your ability to compare networks that use bridges, switches, and routers to separate LAN segments. The basic workings of a bridge and a switch have already been covered in this chapter. To compare these three options, first routing logic is covered. Afterward, comparisons will be made among the three options. Routing is covered more fully in other chapters. For comparison, a router separates two segments in Figure 4-14. The client initiates the same example flow that was...