With my exam in ten days I have to brush up on my subnetting skills. I will be doing this every day till exam day. If you are looking for ways to learn subnetting check out the links and video below by Practical Networking. I highly recommend you watch all of the Subnetting Mastery videos and website. If you have done subnetting before and just need a refresher check the video I included below. The video provides great quick tips.
By far these are the best videos on subnetting. I think being able to do subnetting quickly is a must know for the CCNA exam. I have seen at least one or two questions within the Boson ExSim practice exams that require subnetting knowledge.
The links below are directed to their blog, website and YouTube videos on subnetting. If you want to practice check out subnetipv4.com. It has a clean and simple to use tool that populates random CIDR notation to practice from. In there one has to figure out the Network ID, Broadcast ID and if stuck it can populate the answers.
Now I got to practice to get fast and better at subnetting.