Chapter 5 Exam Essentials

Question 1

Describe the benefits of variable length subnet masks (VLSMs)

Answer 1

VLSMs enable the creation of subnets of specific sizes and allow the division of a classless network into smaller networks that do not need to be equal in size. This makes use of the address space more efficient because many times IP addresses are wasted with classful subnetting.

Question 2

Remember the four diagnostic steps.

Answer 2

The four simple steps that Cisco recommends for troubleshooting are:

1. ) ping the loopback address
2. ) ping the NIC (ip address of local host)
3. ) ping the default gateway
4. ) ping the remote device/server

Question 3

Identify and mitigate an IP addressing problem

Answer 3

Once you go through the four troubleshooting steps that Cisco recommends, you must be able to determine the IP addressing problem by drawing out the network and finding the valid and invalid hosts addressed in your network.

Question 4

Understand the troubleshooting tools that you can use from your host and a Cisco router

Answer 4

The ‘ping 127.0.0.1’ command tests your local IP stack, and ‘tracert’ is a Windows command to track the path a packet takes through an internetwork to a destination. Cisco routers use the command ‘traceroute’, or just ‘trace’ for short. Don’t confuse the Windows and Cisco commands. Although they produce the same output, they don’t work from the same prompts. The command ‘ipconfig /all’ will display your PC network configuration from a DOS prompt, and ‘arp -a’ (again from a DOS prompt) will display IP-to-MAC-address mapping on a Windows PC.