CertExams.com router simulator has the following features:

-Several lab exercises: The labs are particularly useful for candidates preparing for Cisco CCNA Intro, ICND, and CCNA certifications. 40+ labs are available for thorough hands-on preparation.

-Cisco router console simulation: Cisco router console (running Cisco router IOS) is available in a simulated environment. Currently 60+ Cisco IOS router commands are supported. It is expected to give good hands-on experience to those who do not have access to Cisco routers for learning purpose.

-Comprehensive help file: The complete simulator is explained in an easy to use help file. The areas covered in the help file include 1. Supported commands, 2. How to navigate through the lab exercises and router console simulator, 3. Disclaimer

-Flash cards: Flash cards are available while taking several lab exercises. These provide topic help, and useful in properly answering the labs.

-Simulate up to 3 routers: Up to 3 routers can be simulated. After configuration, you can even ping the other routers for proper configuration verification.
Limitations of Demo Simulator: The download contains a demo simulator, and a full version that requires purchasing a key for unlocking the software. The demo has limitations such as limited labs, and limited support for router commands.