Review: Wendell Odom's CCENT/CCNA ICND1 and CCNA ICND2 Guides

Alas the exam has been updated; here is a link to the updated guides (which are for exams after September), which I have not reviewed: I do think Wendell Odom's guides are worthwhile investments; I'll try to get the information about the differences between the old and new exams soon; the main thing is that the CCENT exam will not be available after September; also check out CISCO: Favorite Study Links, which I have to update too.

The third editions of Wendell Odom's two-volume guides, one of the "must haves" for aspiring network engineers are now available. Here's a brief look at both Book 1 (which prepares its readers for the CCENT/ICND1) and Book 2 (which prepares its readers for the ICND2, or, together with Book 1, for the CCNA).

Book One

Wendell Odom's Official Exam Certification Guide: CCENT/CCNA ICND1 (2nd and 3rd editions, CISCO Press, 641 pages) is the first book of his two-volume certification guide. It's designed to prepare one to take the CCENT (the first part of the CCNA exam, which now of course can be taken in two parts).

It begins with a look at network architecture which is layered, and an overview of the "LAN" or local area network. The guide then moves through the network layers, with a look at ethernet cabling (the physical layer, or 'layer 1"), then at switches and associated problems including MAC addressing and collisions (layer 2). This is followed by a discussion of IP (internet protocol) addressing and routing of packets (these happen at layer three in the standard network architecture model), and then of layer four packet control (TCP or transport control protocol where receipt of packets is verified and UDP or user datagram protocol, where receipt is not verified). Finally network address translation for wide area networks (where internal addresses are translated into internet addresses) is discussed. Book 1 also looks briefly at wireless networks and wireless security.

Book Two

Wendell Odom's CCNA/ICND2 (3rd edition, 736 ages, Book 2 of the guide) starts with a look at vlans ("virtual local area networks;" these are just subsections of a network making it possible to subdivide a switch to serve several different networks), followed by a more in depth discussion of network routing and subnets, and then by an explanation of how to set up access control lists, lists which control which kinds of packets are allowed or not allowed by a particular router interface, something not addressed at all in Book 1. Finally readers learn to configure point-to-point wans (wide area networks), frame relay connections, and network address translation. Wireless networking is not addressed in Book 2.

Troubleshooting Help

The final chapters in Book 1's sections on switching and routing look at troubleshooting. In Book 2, chapters three, nine, and thirteen are troubleshooting chapters for switches, routers, and routing protocols. Troubleshooting tips also come at the end of some chapters. In both books, the exam preparation chapter (chapter eighteen in Book 1, chapter nineteen in Book 2) provides several "troubleshooting scenarios" for readers to work through.

Helpful Organization

Self-test quizzes begin most chapters, excepting the troubleshooting chapters in Book 2, and the author has provided a table that maps quiz questions to chapter sections. Appendices provide a helpful glossary of terms as well as answers to study questions. Default configurations for CISCO routers and switches are provided in the appropriate chapters as well.

At the beginning of each book, there is a list of "ICND1 Exam Topics," with the page and part of the book that discusses each identified, followed by a similar list of "ICND2 Exam Topics." Within each chapter of the third edition (Book 2), "key topics" are also identified.

In Book 2, topics from Book 1 that must be addressed briefly are highlighted in grey. The author however points out that while the ICND2 exam might not have a specific question on an ICND1/CCENT (Book 1) exam topic, the background might nevertheless be required to answer an ICND2 exam question. Both books of course are needed for the CCNA which covers both the ICND1 and ICND2 material.

Network Configuration Examples

To make explanations of networking clearer in Book 1, the story of the Flinstone's first network is used. The Flinstones' network is also mentioned occasionally in Book 2 examples.

Overall, Wendell Odom has provided good examples of network configuration problems and generally walks readers through these. Security issues are always dealt with at least briefly. In Book 2 care is also taken to explain the rationale behind switch and router architecture features. I was pleased to get an explanation of why switches come with native vlan (which allows forwarding of packets without vlan headers). as the native vlan feature had made little sense to me. This feature permits telnet traffic packets to be forwarded even though these packets do not have vlan headers on them.

Subnetting Practice

The author reminds readers that, if they wish to pass the exam, they have got to be able to do the math required for subnetting (which uses binary and base 16 arithmetic) and do it rapidly. Subnetting is indeed a large part of the exam, but the books offer adequate practice in subnetting, plus each comes with a CD which allows readers to download pratice tests as well as additional subnetting practice.

Note that there is more subnetting practice in the third edition of Book 1 than in the second edition. In he third edition, a complete unit is devoted to "IP Addressing and Subnetting" with separate chapters devoted to analyzing networks, number systems (binary and base 10) used in subnet masks, analyzinbg subnet masks, designing subnet masks, analyzing subnets, and subnet ids.

How the Guide Stacks Up

Wendell Odom's exam certification guide seems more clear (and of course is more test-focused) than CISCO Press's Interconnecting CISCO Network Devices Part I and Part II. Not enough time however seems to be spent on voice vlans, which are introduced with other vlans in book two. The advantages of separating voice vlans from data vlans using different subnets (which can of course among other advantages improve network security) is glossed over very quickly.

There have been some changes in CISCO architecture from the second to the third edition (for one thing, there are now layer-3 switches) so be careful if you buy an older edition. The third edition of both books is now available.


There are few proofreading errors in the two volumes, though there are a couple of typos which result in misspellings. One troubling oversight (for me at least) was example 15-9, page 493 of Book 1 (second edition). The correct interfaces for example 15-9 on p. 493 were identified in my text, but corrections not in a particular printing are identified in the errata.

Second Edition Error

Now comes the problem: the paste-in code specifies the new ip address for interface fa 0/1 (fast ethernet, the 0/1 port slota) for router 4 as, with a net mask of The interface's current ip address however is This fa 0/1 interface is currently connected to computer 23 whose ip address is also with a net mask of From this net mask it is clear that the first three numbers of this ip address (192.168.4 in the one case and 192.168.2 in the other) along with the first four leading 0s in the binary (base 2) version of the last number that make up the network or subnet portion of the address. However, with the new fa 0/1 address for router 4, these first three numbers will now be different for computer 23 and the connecting router interface, and thus will specify different networks or subnets. What's more, it's the current address of the router 4 fa 0/1 interface that has been specified as computer 23's default gateway (to the wider area network) , and with the paste-in code, this gateway address will no longer be valid. Alas thus, computer 23 will become reachable only via router 2, which will still have an interface on the same subnet as computer 23. What's more, computer 23 will not be able to reply to any packets sent to it since its default gateway will now be misconfigured. Unfortunately this serious misconfiguration is not addressed as a routing problem.

This is fortunately the only major error I've found to date. it's not been corrected in the errata, though it has fortunately been corrected in the third edition. If I notice any others, I'll update this.