The CCNA exam a few years ago consisted only of theory questions so all you had to do was read the book and do some practise exams and you would be fine.
Not any more!
Now I'd say the exam points are around 40% based on your hands on labs and knowledge of the Cisco IOS. For this reason you must know your way around all the CCNA level configuration and troubleshooting commands.
Here are your options:
1. Get your own rack – the best option if you have the money. You need 3 routers and 2 switches plus the cables. I cover more details on my site http://www.ccnahomelab.com
2. Use Packet Tracer – officially available to Cisco Academy Students only. This simulates common router and switch models. It isn't perfect and many commands are missing and output is never as expected but for CCNA studies it's more than adequate.
3. GNS3 – a famous router emulator available from from the site http://www.gns3.net. You still need to get your own IOS and it won't emulate switches. It's free which is very cool.
4. Use a live rack. You won't find many active CCNA and CCNP live racks but you can find lots of CCIE racks. You only need to use two of the switches and three of the routers so don't be intimated by the name CCIE. I use:
http://www.mindtechcom.com and at $1.50 an hour it's a steal.
5. Router simulators – I'm thinking of Boson network simulator and Gambit Comms offering. Bosons CCNA net sim is $179 or $349 for their CCNP version.
These were all the rage BEFORE GNS3 came along and Packet Tracer. Personally I don't recommend them due to the fact they are simulating what a router and switch does and often you have alimited amount of commands to choose from.
6. IOU – this is an internal tool used by Cisco which has leaked out onto the web. You need to know Unix or Solaris commands to install and use it. It runs actual Cisco IOS which is great but as I said – it's illegal to use and you need to be fairly techie.
So there you go. The choice is yours. If you plan to go beyond CCNA then a home rack is the way to go. Otherwise make do with GNS3 or Packet Tracer with some extra time on a live rack hosted somewhere for switching practise.
Hope it helps