Troy’s checklist for preparing for the CCNA: Objective 5

July 6, 2009 at 4:36 pm | Posted in Cisco | 1 Comment
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Hello, intrepid CCNA seekers. I salute your persistence if you’ve stuck with me this far! This week we venture into the wild and woolly world of wireless. Specifically we cover the following: Objective 5 of 640-802, Explain and select the appropriate administrative tasks required for a WLAN. It’s a short and sweet objective, especially compared with the whopper that was Objective 4.

(Here’s the previous coverage of Objective 1, Objective 2, Objective 3, Objective 4 Part 1, and Objective 4 Part II. The full list of CCNA objectives is at https://cisco.hosted.jivesoftware.com/community/certifications/ccna/ccna_exam?view=overview.)

First you should know all of the major standard creating and regulatory bodies that influence 802.11 (WLAN) networking:

  • Wi-Fi Alliance (no, they have nothing to do with your old record player, that’s Hi-Fi) – The Wireless Fidelity (Wi-Fi) Alliance is an organization formed to provide interoperability between different WLAN vendors.
  • IEEE – the Institute of Electrical and Electronics Engineers (IEEE) is a non-profit worldwide organization that creates standards for various industries, including information technology (IT) and telecommunications.  802.11 wireless networking standards are defined by the IEEE.
  • FCC – the Federal Communications Commission (FCC) is a U.S. government agency that regulates communication standards in the areas of wire, television, cable, and satellite communications. It also regulates the use of radio frequencies (RF) and power of transmitters.

Know all of the following terms and how the components make up a wireless network:

  • Ad Hoc network
  • Infrastructure network
  • ESS, BSS, IBSS
  • SSID

Also, know how to create an ESS. (If you put the same SSID on each access point, they will all be in the same ESS while each maintains its own BSS.) If you need some background, here’s a good basic article from Cisco Press: Wireless LANs: Extending the Reach of a LAN

Before I continue, here’s a joke.

Q. What are the three most important things to understand about wireless networking?

A. Security, security, security, security, and security.

Seriously, folks, there is a lot of wireless security to know. If you only have room in your memory for a few key facts, then here’s where to focus. It might help to generate a timeline of each security technology and make a note of 1. what it features, 2. what it replaced or supplemented, and 3. where it’s currently implemented, if at all.

  • Know the common wireless standards: 802.11, 802.11g, and 802.11b.
  • Be familiar with the components of WEP, WPA, and WPA-2, including the differences between these technologies.
  • WPA-2 operates in two modes: Enterprise and Personal. Know what encryption is used in each mode. In Enterprise it uses AES/CCMP. In Personal it uses a shared key.
  • WPA (the older, less powerful technology) uses MIC/TKIP for encryption.
  • WEP  uses static shared secrets and is the weakest security listed here.
  • IEEE 802.11i is an amendment to the 802.11 standard that is meant to address the weaknesses of WEP. WPA2 is an implementation of 802.11i.
  • LEAP is a form of EAP that uses passwords and a RADIUS server. It can also dynamically change the WEP keys, if you are also using WEP.
  • Be familiar with security concepts like MAC address filters, port-based access control, and wireless intrusion detection and prevention.
  • Understand what is meant by wireless security terms like sniffing and war driving.

That’s pretty much it! Objective 5 is not a major part of the exam, so you can focus your study on these topics for good coverage.

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