Welcome to the Cisco Learning Network!
I understand you want to start your CCDA journey.
Always a good place to start is with an overview and the exam topics, so you are aware of what you need as pre-requisites and what you need to study in order to pass your CCDA certification. You can check the overview of the CCDA certification and download the Exam Topics (PDF. format) at the following links:
Also you can find here at the Cisco Learning Network valuable FREE study material and practice at the following links:
Additionally here at the Cisco Learning Network you can find a very good FREE "Practical Network Design Fundamentals" webinar series, so you start getting more in dept knowledge that will be very beneficial for your CCDA studies. You can check it out at the following link:
Its good that you already have the CCDA book from Cisco Press, other self study resources you might want to consider from Cisco Press for the CCDA certification exam are here: CCDA Training - Cisco Certification - Cisco Press > Certification Info
Finally, I would advice you to join the "CCDA Study Group" here at the Cisco Learning Network, so you can go ahead ask your questions related to your CCDA preparation and also read questions/answers from other community members. You can join the CCDA study group from the following link:
Finally, I hope you find this information helpful for you and I wish you all the best in your CCDA certification studies.
I am glad I could help you out and more glad to know that you are on the right track.
I understand you want to understand what other Cisco certification tracks are available for security and hardening.
In that case, I recommend that you check the complete offering of Cisco certification tracks available at the following link:
There you will see all the complete tracks for Associate, Professional and Expert levels including Specialist tracks available within Cisco.
Also at the Cisco Networking Academy, you can find FREE courses that you can take and guide you toward your professional needs. You can check them out at the following link:
I hope this will be helpful for you.