Here are 8 pages of study questions to help you study for "Interconnecting Cisco Networking Devices Part 1 (100-105)" which is used both as the CCENT exam and basically the "first half" of the full CCNA exam.
The idea for this came out of people taking the 100-105 exam and coming away with the feeling that the Official Cert Guide did not cover everything on the exam. This is by design, as I've overheard a Cisco employee explain that while everything in the OCG is fair game for the exam, not everything for the exam comes from the OCG. The solution, therefore, is to get an understanding of the topics that extends outside the OCG and pulls information from Wiki articles, Cisco whitepapers, IETF RFCs, and other freely-available sources for this information.
To answer the questions, we recommend hitting a search engine and going to any Wikipedia or Cisco.com links about these topics. Read those resources and then see if you can answer the questions without referring back to the resources, except to check your answers.
Here are the pages, found in this forum:
https://www.networking-forums.com/guides-and-labs/cabling-osi-and-theory-for-(100-105)-ccent-ccna/
https://www.networking-forums.com/guides-and-labs/layer-two-topics-for-(100-105)-ccent-ccna/
https://www.networking-forums.com/guides-and-labs/ipv4-for-(100-105)-ccent-ccna/
https://www.networking-forums.com/guides-and-labs/ipv6-for-(100-105)-ccent-ccna/
https://www.networking-forums.com/certifications-and-careers/ospf-for-interconnecting-cisco-networking-devices-part-1-(100-105)-ccent-ccna/
https://www.networking-forums.com/guides-and-labs/routing-for-interconnecting-cisco-networking-devices-part-1-(100-105)-ccent-ccna/
https://www.networking-forums.com/guides-and-labs/ios-commands-for-(100-105)-ccent-ccna/
https://www.networking-forums.com/guides-and-labs/scenarios-for-(100-105)-ccent-ccna/
Added a video to announce this area: https://www.youtube.com/watch?v=JYE_UHMzX3s&feature=youtu.be