Boson overall is fairly decent. I used the copy that came with Wendell Odom's CCNA study books (ICND1/ICND2). The only problems I found that I didn't like with Boson, is the fact that I run into questions that have the wrong answers as being correct. Additionally the simulation type questions are fairly limited in respect to the limited way you can solve them.
As for Packet Tracer, as far as I know it is only available to Cisco students, but it is an excellent tool. I've done all kinds of fictitious networks, and the practice simulations that Cisco provides are awesome, they really give you a real world feel for working with LANs and WANs. The CLI is awesome, you can do just about everything in Packet Tracer that you can do on a real switch or router. If you do have access to Packet Tracer, definitely create your own networks and some based on the examples in Wendell Odom's books, you'll learn a lot more that way.
Just a heads up - the version of NetSim that comes with the Cisco Press book is a limited edition. The full version sold by Boson supports many more commands and is updated frequently. You can see a list of supported technologies here: http://www.boson.com/AboutNetSim.html.
Please do note that Cisco recommends that certification candidates train with Cisco Learning Partners for authorized course offerings that align with current Cisco exam topics. A current list of Cisco Learning Partners can be accessed at http://www.cisco.com/go/class_locator where the necessary training can be provided.
Also, Cisco Press products are the only authorized self-study publications that align with Cisco learning paths. These products include simulation material that again many candidates have found useful for acquiring their certification. To see the catalog of publications and other resources visit http://www.ciscopress.com.
There are also several other sites on Cisco.com that you may find useful:
Cisco Tools and Support: *Download free or fee-based softwares or configurations
NetPro Community: *Another community of Networking Professionals and Experts in the field
Cisco Products and Services: *You can click on the Products and Services listed on this page and you may find some good tips & other tools
Free Web-Events, Web Cast, Networks Information
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